Hydrogen effusion measurements reveal that the total hydrogen concentration in ZnO ranges from 5.2×1016 cm−3 for single crystal ZnO to 3×1021 cm−3 for polycrystalline ZnO thin-fims. From the H effusion spectra the hydrogen chemical potential is determined as a function of the H concentration that can be related th the H density-of-states distribution. Single crystal ZnO exhibiting the lowest H concentration reveals six peaks in the H density-of-states located between 0.59 and 1.4 eV below the H transport site. With increasing H concentration the amount of H accommodated with binding energies larger than 1.0 eV increases significantly.

Zinc oxide (ZnO) has shown great promise as a wide band gap semiconductor with optical, electronic, and mechanical applications. Recent first-principles calculations and experimental studies have shown that hydrogen acts as a shallow donor in ZnO, in contrast to hydrogen's usual role as a passivating impurity. The structures of such hydrogen complexes, however, have not been determined. To address this question, we performed vibrational spectroscopy on bulk, single-crystal ZnO samples annealed in hydrogen (H2) or deuterium (D2) gas. Using infrared (IR) spectroscopy, we have observed O-H and O-D stretch modes at 3326.3 cm−1 and 2470.3 cm−1 respectively, at a sample temperature of 14 K. These frequencies are in good agreement with the theoretical predictions for hydrogen and deuterium in an antibonding configuration, although the bond-centered configuration cannot be ruled out. The IR-active hydrogen complexes are unstable, however, with a dissocation barrier on the order of 1 eV.

A mechanism for transport and diffusion of H in a silicon solar cell by PECVD SiN:H process is proposed. Plasma-induced surface damage “stores” H during the nitride deposition, which is driven into the bulk of the solar cell during metal-contact firing. Theoretical and experimental results are given that verify this mechanism.

A brief survey of some of the recent results of recombination-induced defect reactions involving hydrogen in 4H and 6H-SiC is given. A variety of outcomes of such reactions have been observed in hydrogenated 4H and 6H-SiC polytypes under optical excitation at reduced temperature. A few different non-metastable hydrogen-defect complexes can form, including hydrogen complexes with Al and B acceptors, hydrogen complex with Si vacancy, as well as some other non-identified complexes. Electrical measurements indicated strong recombination-induced passivation of the electrical activity of aluminum and boron acceptors in SiC. This passivation resulted in the reduction of the net free hole concentration and even inversion of the conductivity type. It is suggested that optical excitation causes a long-range migration of hydrogen followed by its capture in one or another kind of defect complexes. Further insight in the formation of specific complexes as a result of recombination-induced defect reactions is provided by thermal admittance spectroscopy. Energy gap levels in the regions that remained p-type after hydrogenation as well as in the regions where the conductivity was inverted by the recombination-induced passivation are investigated.

The use of gettering techniques, with precise location of the gettering regions, has become crucial for device manufacturing. Helium-induced cavities have been shown to getter metallic impurities very effectively, but suffer from the drawback of requiring relatively high He doses. In this work, He-implanted Cz wafers of varying resistivity were subjected to hydrogen plasma hydrogenation prior to the cavity-formation anneal. We focus our studies on the cavity layer interactions with metal impurities. XTEM images reveal that hydrogenation increases the cavity radius. Our SIMS results show that the doping level has no influence on the metal gettering efficiency while the addition of plasma hydrogenation tends to decrease it. However, the efficiency can be controlled with the cavity radius which is interesting for future applications of the technique.

The effect of hydrogen treatment on room temperature electric properties of narrow-gap semiconductor thin films ZnxCdyHg1−z−yTe (0 < x < 0.50, 0.20 < y < 0.40) is investigated for the first time. ZnCdHgTe films of 2 – 5 [.proportional]m thickness were grown on glass substrates by pulsed laser deposition technique. As-grown films were thermally treated in the flow of molecular H2 at 200°C during 24 hours. Comparison between electric characteristics measured before and after hydrogenation showed sufficient changes of the film resistance and appearance of photosensitivity in the visible wavelength range. Study of current-voltage characteristics of the films revealed appearance and significant change of diode-like properties.

The geometry of hydrogen intercalation sites in rutile TiO2 has been examined with first principles calculations. The calculations predict a new intercalation site, which is consistent with current experimental data. The apparent contradictions between spectroscopic, diffraction and magnetic resonance data are resolved by taking into account the strong local distortions of the structure induced by localization of charge donated by hydrogen. In particular the predicted OH vibrational frequency is in excellent agreement with the experimentally measured value. A similar local geometry is predicted in the presence of trivalent counter ions but with a preferential site occupancy consistent with the local symmetry implied by spectroscopic measurements of aluminium substituted titania.

The anharmonic contributions to the vibrational frequency of various H-H, N-H, O-H, and C-H bond configurations are investigated using first principles calculations. While harmonic approximation can be accurately used to calculate the local vibrational mode of most microscopic configurations, the configurations involving strong X-H bond are exceptions because of the exceptionally light mass of the H atom. We will explicitly present the magnitude of the anharmonic contributions to the total frequencies associated with X-H bonds in free molecules as well as in semiconductors defects.

We have developed a model to account for the effects of hydrogen and voids on the structural stability of silicon thin films. The model is based on both experiments and theory. First, hydrogenated amorphous silicon films (a-Si:H) with various hydrogen contents were obtained by Plasma Enhanced Chemical Vapor Deposition. A linear correlation between hydrogen content and void fraction was observed. By tuning the deposition conditions, polymorphous silicon films with hydrogen contents up to 15%, very small void fractions (0.5%) and excellent electronic properties were also obtained. Density Functional Theory (DFT) calculations were performed to determine the formation energy for four types of silicon tetrahedra of the form Si-SinH4−n (n=1, 2, 3, 4). In our model, these tetrahedral units are considered as the building blocks of the silicon thin films. Considering a homogeneous distribution of hydrogen in the solid, the proportion of the different SiSinH4−n tetrahedra as a function of the hydrogen concentration was calculated. Then, the formation energy of hydrogenated amorphous silicon (a-Si:H) was calculated as a function of the hydrogen content and for various porosities. The model predicts that hydrogen incorporation does render the a-Si:H structure unstable for different hydrogen contents depending on the void fraction. Our results show that polymorphous silicon films with hydrogen concentrations up to 15% can be as stable as standard amorphous silicon with 2% hydrogen content, provided that the presence of hydrogen is not associated with the incorporation of porosity in the film.

Monocrystalline and multicrystalline silicon wafers were investigated with boron doping levels in the range 1015 cm−3 to 1016 cm−3, respectively. Hydrogenation of the samples resulted from hydrogen-rich silicon nitride deposition by plasma enhanced chemical vapour deposition on the surface of the wafers. Passivation effects are observed after annealing and evaluated using minority carrier diffusion length (L) measurements, light beam induced current scan maps and lifetime (τ) measurements, by the contact-less phase shift technique. When applied at various excitation frequencies the phase shift technique leads evaluate the surface recombination velocity (S) and the actual bulk lifetime.

It was found, in multicrystalline silicon that isolated intragrain defects are well passivated while at grain boundaries and dislocation clusters deep levels are transformed into shallow levels. As a consequence L increases up to 80 % after firing the samples which the back surface was covered by a 2 μm thick aluminium layer. S decreases below 500 cm/s at the front surface covered by the hydrogen rich silicon nitride layer.

Hydrogen (deuterium used as tracer) diffusion experiments were performed on undoped and boron doped diamond films ([B] = 1019and 1020 cm−3) grown by plasma CVD or hot-filament assisted CVD. The samples were exposed either to a radiofrequency plasma or a microwave plasma at different temperatures between 400°C and 900°C. The deuterium profiles were analysed by secondary ion mass spectrometry (SIMS). The deuterium diffusion was explained mainly in term of trapping on intergranular defects. The passivation of boron acceptors, by B-D complex formation in the deuterium diffused superficial layers of the diamond films, was followed by electrochemical and mercury probe capacitance measurements. The results suggest a strong decrease of the free carrier density, which is in accordance with passivation of free carriers by deuterium trapping on dopant.

One of today's challenges to enable the improved electrical performances and reliability of microelectronic devices consists in controlling impurities contamination: hydrogen appears to be present in most (if not all) the processes steps of the devices making (ambient atmosphere, or associated with AsH3 -VPE or AsCl3 -VPE for example in GaAs based devices,…). Hydrogen induced reliability has already been investigated for many Si or GaAs based technologies ((C)MOS, FET, HEMT, PHEMT as well as HBT devices). These effects of hydrogen on electrical behavior and on long term reliability are very difficult to understand because of the different nature and ionic association of hydrogen (H, H+, H-, H2, or associated with impurities (Ge-H, Be-H, C-H,…). Most of these studies make use of IR, SIMS, Hall measurements: in this paper, we use low frequency noise measurements, associated with static as well as dynamic characterization to identify the degradation process in GaInP/GaAs Heterojunction Bipolar Transistors (HBT supplied by Thomson LCR). The presence of Hydrogen has been identified by DLTS at the LPSC laboratory (Meudon, France). The influence of passivation (SiN and GaInP ledge) on the reliability associated with Hydrogen has been one of the first improvements on HBT devices. Low-frequency noise measurements have been performed in the range of 250Hz to 100 kHz. The noise spectra evolutions (current and voltage noise sources at the input of the devices) allowed us to identify the activation process responsible of the static and dynamic rise and fall of the HBT's current gain. Chemical reactions of C-H complexes have been proved to be the processes responsible of this degradation. Additive reliability tests have been performed on two sets of devices (featuring different emitter length) under two distinct stocking conditions (temperature and biasing of the devices) leading to different junctions temperatures: low-frequency (LF) noise measurements, associated with static and dynamic S parameter measurements led to the same conclusion about the involved chemical reaction. We found that C-H complexes break, and H diffusion towards the extrinsic surface of the device has been observed on the measured leakage currents. Sealed devices have proved to get the same degradation signature than on wafer devices: Hydrogen is assumed to be present in high concentration levels in the device layers, and reacts under thermal and electrical stress.

We have studied the local motion of hydrogen in the neighborhood of carbon and platinum impurities by observing the stress-induced reorientation and subsequent recovery of two H-related (H-C and Pt-H2) complexes in Si, using deep-level transient spectroscopy (DLTS) under uniaxial compressive stress. We notice two interesting differences in hydrogen motion around carbon and platinum atoms. The first one is a difference in the temperature where stress-induced reorientation occurs. That of the H-C complex occurs at high temperatures above 250 K, while it occurs at low temperatures around 80 K for the Pt-H2 complex. The second difference is the effect of charge state of the complexes on their stress-induced reorientation and subsequent recovery. It occurs preferentially when an electron occupies the level of the H-C complex, but the Pt- H2 complex has the reverse effect of level occupancy. These differences are discussed from viewpoint of different atomic configurations and electronic states of two H-related complexes.

P type Czochralski (Cz) and float-zone (FZ) grown silicon wafers were investigated with doping levels of 5×1014 and 2×1015 cm−3, respectively. Hydrogen ions are implanted at a dose of 2×1016 cm−2, at energies in the range 20 to 250 keV and are accumulated at depth Rp in the range 0.2 to 2.4 μm. After implantation the wafers are annealed between 350 and 600°C for 30 min, under argon flow. It is found that a graduated n-p junction is formed, and after metallization a photovoltaic device is obtained, which works like a solar cell. SIMS analysis shows that, around Rp, hydrogen concentration achieves 1021 cm−3. I-V and C-V curves confirm the formation of a N-type layer in which the donor concentration is about 5×1017 cm−3. When the samples are annealed at temperatures higher than 550°C the counter-doping vanishes. The observed behaviour of hydrogen is irrespective of oxygen concentrations in the wafers as it occurs in Cz (oxygen rich) like in FZ (oxygen poor) wafers. If the wafers are ion implanted with helium at the same dose and energy no junction appears. It is concluded that the agglomeration of hydrogen in silicon after ion implantation at a dose exceeding 1016 cm−2 gives rise to the formation of shallow donors.

It is well known that diffusion of deuterium in boron-doped diamond results in the passivation of boron acceptors with the formation of (B,D) complexes. In this work, we show that deuteration of boron-doped diamond can induce a p-type to n-type conversion under certain conditions. The n-type conductivity is governed by the ionization of shallow donors with a ionization energy of 0.34 eV. This is well below the lowest ionization energy of donors found up to now in diamond (0.6 eV for phosphorus donors). The electrical conductivity and the electron mobility can be as high as 6 S/cm and 430 cm2/Vs at 300 K. The reversibility of the effect under thermal annealing and the necessity of excess deuterium to trigger the n-type conductivity suggest that deuterium is involved in the formation of the shallow donors. The present status concerning the understanding of their origin is discussed. In addition, we have found that, contrary to previous conclusions, deuterium can diffuse in type Ib diamond. The conditions where this diffusion is observed are presented.

H2 is a fascinating molecule whose properties revealed the influence of nuclear spin on the molecular wave function in the 1920s. As an interstitial defect in Si, the H2 molecule has given rise to a number of perplexing puzzles since the discovery of its vibrational spectrum. The absence of an ortho-para splitting for the H2 vibrational line and an apparent low symmetry found in stress experiments misled several researchers into thinking that interstitial H2 in Si must have a barrier to rotation. Our discovery of a new vibrational line for HD in Si and its interpretation, along with the recognition that certain transitions are possible for HD, but not for H2 or D2, establish that H2 in Si is a nearly free rotator after all. Additional puzzles such as the anomalous intensity of the HD line, the absence of an isotope dependence for the uniaxial stress splitting of the H2 and D2 vibrational lines, and the properties of an O-H2 complex are also explained naturally. Recent Raman studies confirm that interstitial H2 in Si is a free rotator but raise interesting new questions about the diffusivities of the ortho and para species.

Characterization of defect and impurity reactions, dissociation and migration in semiconductors requires detailed understanding of rates and pathways of vibrational energy flow, of energy transfer channels and of coupling mechanisms between local modes and the phonon bath of the host material. Significant progress in reaching this goal has been accomplished in recent landmark studies exploring the excitation and dynamics of vibrational states associated with hydrogen in silicon. We describe recent experiments which measure the vibrational lifetime of the Si-H bond in various defect configurations and show the relationship between these lifetimes and silicon MOSFET reliability.

In order to verify Van de Walle and Jackson's theory on the isotope effect of the Si-H/D bonds resistant to hot-electron excitation [Appl. Phys. Lett., 69, 2441 (1996)], we measured the Si-H, Si-D, and other vibrational modes in oxidized silicon wafers annealed in hydrogen and deuterium using Fourier Transform Infrared (FTIR) spectrometry. Our FTIR data suggest that the frequency for the Si-D bending mode at the SiO2/Si interface is 490 cm−1. Our experimental data support Van de Walle and Jackson's theory with some modification. Their theory is correct for the experiments of breaking Si-H/D bonds using scanning tunneling microscope (STM) where no oxide is involved. In the SiO2/Si case, the de-excitation of the Si-D bond may be due to the energy coupling from the Si-D bending mode to two vibrational modes; i.e., the Si-O TO mode and the Si-Si TO phonon mode. Van de Walle and Jackson only pointed out coupling to the Si-Si TO phonon mode. The strongest coupling might happen between the Si-D mode and the Si-O TO mode. Therefore, the oxide may play a crucial role in energy dissipation of the Si-D bond in metal-oxide-semiconductor (MOS) devices.

Hydrogen is an omnipresent impurity in semiconductors, often associated with other impurities and native defects, strongly affecting their electronic properties by passivating deep and shallow levels, or activating isoelectronic centers, and can be intentionally or unintentionally incorporated. On the other hand, nitrogen has profound effects on the electronic structure of conventional III-V compounds: just a few percent of N can drastically lower the band gap of GaAs making it suitable for long-wavelength optical devices; isovalent doping of GaP by N leads to a quasidirect band gap with enhanced optical functionality. The large difference in electronegativity between N and other group V elements is expected to couple with the high chemical activity of H, raising crucial questions about the behavior of H in dilute nitride alloys that theories of hydrogen in conventional semiconductors or in commom-anion nitrides are unable to answer. Here we show that N can qualitatively alter the electronic behavior of hydrogen: In GaAsN, an H atom bonds to N and can act as a donor in its own right, whereas in GaAs and GaN, H is amphoteric; Nitrogen also stabilizes the complex, that is otherwise unstable against the formation of interstitial H2 molecules, reversing the effect of N on the band gap of GaAs, allowing us to interpret several recent experiments.

An instrument for prompt gamma-ray activation analysis (PGAA) at the NIST Center for Neutron Research has proven useful for the measurement of hydrogen and other elements in a variety of materials. The sample is irradiated by a beam of low energy neutrons. Gamma-rays emitted by atomic nuclei upon neutron capture are measured and elemental concentrations determined by comparison with appropriate standards. The detection limit for hydrogen is < 5 mg/kg in most materials, and 2 mg/kg for hydrogen measured in silicon. The instrument has been used to measure hydrogen mass fractions of < 100 mg/kg in high purity germanium, and < 10 mg/kg in quartz. More recently PGAA has been used to measure hydrogen in 1 μm thick porous thin films on a silicon substrate, and in crystals of silicon carbide and cerium aluminate.