Critical evaluation of the status of the areas for future research regarding the wide band gap semiconductors diamond, gallium nitride and silicon carbide
The deposition of monocrystalline diamond, at or below 1 atm total pressure and at a temperature T<1273 K, has been achieved on diamond substrates; the deposited film has been polycrystalline on all other substrates but the achievement is no less significant. For electronic applications, heteroepitaxy of single-crystal films of diamond, an understanding of mechanisms of nucleation and growth, methods of impurity introduction and activation, and further device development must be achieved. Stoichiometric gallium nitride free of nitrogen vacancies has apparently not been obtained. Thus, knowledge of the defect chemistry of this material, the growth of semiconducting films on foreign substrates, and the development of insulating layers and of their low temperature deposition as well as device fabrication procedures must be achieved. By contrast, all of these problems have already been solved for silicon carbide, including the operation of a MOSFET at 923 K - the highest operating temperature ever reported for a field-effect device. However, considerable research remains to be done regarding the development of large silicon carbide substrates of ohmic and rectifying contacts, of new types of devices, and of low temperature techniques for the deposition of insulating layers. Fugitive donor and acceptor species in unintentionally doped samples must also be identified and controlled.
Davis, RF; Sitar, Z; Williams, BE; Kong, HS; Kim, HJ; Palmour, JW; Edmond, JA; Ryu, J; Glass, JT; Carter, CHJ
Materials Science & Engineering B: Solid-State Materials for Advanced Technology
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