Improved mobilities and resistivities in modulation-doped p-type AlGaN/GaN superlattices

摘要

The transport properties of modulation, shifted modulation, and uniformly doped Al_(0.20)Ga_(0.80)N/GaN superlattices are presented. The modulation-doped sample is doped only in the AlGaN barriers. The shifted-modulation-doped sample has its dopants shifted by one-quarter period. Measurements reveal a strong improvement in mobility and resistivity for the modulation-doped and shifted-modulation-doped structures versus the uniformly doped structure. The modulation-doped sample has a mobility of 9.2 and 36 cm~(2)/V s at 300 and 90 K respectively and a very low resistivity of 0.20 and 0.068 Ωcm at 300 and 90 K, respectively. Capacitance-voltage profiling shows multiple two-dimensional hole gases. The results are consistent with a reduction of neutral impurity scattering for modulation-doped structures as compared to uniformly doped structures.