Silicon nitride deposited by plasma-enhanced chemical vapor deposition (PECVD) from SiH4 and NH3 is not crystalline Si3N4 with a specific stoichiometric ratio, but rather SiNxHy, an Amorphous network in which the N/Si ratio can vary from zero in Amorphous Si (a-Si) to almost two. The rate at which injected electrons are trapped in SiNxHy decreases by over 103 when N/Si is increased from 4/3 to the N saturation point, and the trapping centers are therefore likely to be Si dangling bonds. Trapping is undesirable in semiconductor devices except in memory applications, because it shifts the device's flat-band voltage, although in a-Si thin-film transistors (TFT's) the nitride trapping rate can easily be made Much smaller than the rate of electron trapping in deep states of the a-Si. When deposition plasma chemistry is driven to the N-saturation point, SiNxHy has a trapping rate lower than that of the best PECVDSiO2, although this is still 104 above that of thermal oxide grown on single-crystal Si. N-saturated deposition requires not only a high NH3/'SiH4 feed ratio, but also sufficient plasma power to activate the NH3 so that it will completely consume the SiH4 in formation of the tetra-aminosilane [Si (NH2) 4] precursor molecule. Then, the Si in the Amorphous network becomes entirely bonded to N rather than to both H and N, and NH groups act like O does in SiO2 to lower the coordination of the network and thus avoid dangling bonds.