Dual implants of (P+ + Si+) through thin Si3N4, layers have been studied. The phosphorus dose has a marked effect on the electrical properties of 6 × 1012 Si+ cm−2. Optimum electrical activation occurred at a phosphorus dose well below that required to produce an amorphous layer and depended on whether a furnace or a rapid thermal anneal was performed. Good control over the tail of the electron concentration profile was obtained for doses of phosphorus in the range 6 × 1012 to 1 × 1014 ions cm−2.

Rapid thermal anneal (R.T.A.) by halogen lamps has been carried out to activate Si29 implants in semi-insulating InP substrates with the aim of realizing good contact areas at low depth (0.1 μm). To better understand the electrical behaviour of Si observed in these conditions, and to try to increase the electrical activity we performed dual implantations (As + Si or P + Si). The crystallographic disorder remaining after anneal and its influence on the electrical properties are discussed. The uniformity of activation has been evaluated by Hall effect and specific contact resistivity cartographies both for mono-implantations and for dual implantations.

Rapid thermal annealing (RTA) technology offers potential advantages for the processing of ion implanted GaAs. High energy implants of 300 keV or above are used for power MESFETs as well as in the ohmic contacts for low noise devices. The purpose of this paper is to investigate and characterize the RTA of Si implants into LEC GaAs using implant energies of 300keV and above, and a range of doses from 2.3 ×1012 to 3×1014 /cm2. The wafers were analyzed using capacitance-voltage and Hall measurements. Factors which cause variability in pinchoff voltage are identified and an RTA process comparable to conventional furnace annealing is presented for low dose implants. Superior implant activation is observed for higher dose implants through the use of higher annealing temperature.

It is shown here that high-dose Zn implants in semi-insulating InP substrates, after conventional furnace anneals lead to the following anomalies : step-like atomic Zn and carrier distributions and the presence of electrically inactive Zn at all depths of the profiles.

Zn anneal behavior is compared using conventional furnace anneals, and two different types of short-time anneals ; rapid furnace anneals(RFA)at ∼750°C with a rise-time of ∼ 50 s, and halogen lamp rapid thermal anneals (RTA)also at ∼ 750°C with a rise-time of ∼ 4 s. We have established that the Zn anomalous diffusion is an instantaneous phexomenon occuring during annealing transients. Also, we have further shown that RTA would help to smooth carrier profiles by removing the step in carrier (but not in atomic Zn) distribution.

The properties of differently Zn co-implanted layers (Zn plus P, Zn plus In and Zn plus As) after RTA, and of P or In implanted Zn doped InP substrates after different anneals,have been studied. We have shown that the presence of electrically inactive Zn in the depth of the layers is a consequence of interaction between Zn atoms and defects. A simple model based on the density of damage deposited in the layer during implant, has been proposed and discussed.

Rapid thermal diffusion of zinc into semi-insulating GaAs from spin-on zinc silica film is investigated. The rapid thermal diffusion is performed for various diffusion times (5 to 25 sec) and temperatures (800° to 950° C) with tungstenhalogen lamps as the heat source. The sheet resistivity, surface hole concentration and mobility of these zinc diffused layers as measured by Van der Pauw technique shows the formation of shallow p+ layer. The surface morphology of these diffused layers are observed in a low voltage Scanning Electron Microscope (SEM) and the depth profile of diffused impurities are determined by Secondary Ion Mass Spectroscopy (SIMS). Nonalloyed ohmic contacts are formed on these zinc diffused layers and the contact resistivity is determined by the Transmission Line Method (TLM).

A process for Zn diffusion into GaAs during rapid thermal processing has been developed using Zn doped tungsten silicide as the diffusion source. The WSi:Zn is a sputter deposited, solid source layer that undergoes capless annealing in a quartz-halogen lamp system. For a given time and temperature the diffusion of Zn into GaAs is controlled by both the Zn concentration and the W/Si ratio in the film. Tungsten-rich films are Zn concentration “independent” while Si-rich films are Zn concentration “dependent.” Changing the film composition allows shallow Zn diffusions at either a low or a high temperature. Deep Zn diffusions are possible through higher temperatures or longer anneal times for any given WSi:Zn composition.

A two step rapid thermal anneal (RTA) has been studied for activating Be implanted GaAs, where a short duration, high temperature step is used to electrically activate the Be followed by a longer, low temperature anneal for lattice regrowth. p-n diodes show a substantial reduction in reverse diode leakage current after the low temperature second step anneal, when compared to a single step RTA or to furnace annealing (FA). For low energy Be implants, no difference in elecrical activiation between the two step anneal is observed. Raman studies demonstrate that residual substrate impurities and high Be concentrations inhibit restoration of single crystal lattice characteristics after RTA. Lattice quality is shown not to limit diode characteristics in the RTA material.