Subband Structures of N-Channel Inversion Layers on III–V Compounds –A Possibility of the Gate Controlled Gunn Effect–

Multi-subband structures of n-channel inversion layers on the surface of p-type III–V compounds are calculated by a variational method. Nonparabolicity is taken into account in the bulk dispersion relation of the \(\varGamma\)-valley. When the surface electron density is low, electrons occupy only the subbands in the \(\varGamma\)-valley, while when it exceeds certain critical value, most electrons occupy the ground subband in the second minimum valleys. From this behavior, the working condition of the Gunn effect in the system can be changed by applying the gate voltage in the MOS structure. The critical surface electron density depends on the charge density in the depletion layer and the surface orientation, but in case of GaAs, it is about 7×10 12 cm -2 for typical operating conditions.

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