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Doped films of amorphous silicon nitride have been prepared by the glowdischarge technique over a wide range of ammonia-silane mixtures. Phosphorus-and boron-doped specimens were produced by admixing measured amounts of phosphine or diborane during deposition. Interstitial doping of specimens was attempted with sodium by ion-beam implantation, and with lithium by evaporation and in-diffusion. The electrical conductivity and the optical gap of these specimens have been determined as a function of the volume ratio of ammonia to silane. All four dopants raise the conductivity of low-nitrogen-content specimens to about l o w 2 R -* cm-' at room temperature, without changing the optical gap. With increasing nitrogen content the effect of phosphorus, boron and sodium doping decreases rapidly. In contrast, incorporation of lithium significantly increases the room-temperature conductivity of even high-nitrogen-content films. By careful control of the preparation conditions, near-stoichiometric, optically transparent specimens have been produced in which the room-temperature conductivity has been increased by fourteen orders of magnitude through lithium doping.

Doped films of amorphous silicon nitride have been prepared by the glow discharge technique over a wide range of ammonia/silane mixtures. P- and B-doped specimens were produced by admixing phosphine or diborane during deposition. Interstitial doping was attempted by Na-ion implantation, and by in-diffusion of evaporated Li. For values of the ammonia/silane volume ratio R < 10−2, the optical gap remains unchanged and all the above dopants raise the room temperature conductivity to σRT ≅ 10−2(Ω cm)−1. With increasing R the efficiency of P, B and Na doping decreases rapidly. However, incorporation of Li continues to significantly increase σRT at higher R where the optical gap approaches 5eV. Near-stoichiometric, transparent specimens have been prepared with σRT increased by up to 14 orders of magnitude by Li doping. A discussion of the doping results is given.

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