Optical and electrical properties of (1-101)GaN grown on a 7° off-axis (001)Si substrate

Uniform growth of (1-101)GaN was performed on coalesced stripes of GaN which had been prepared by selective metalorganic vapor phase epitaxy on a 7° off-axis (001)Si substrate via an AlN intermediate layer. The cathodoluminescence spectra at 4 K exhibited a donor bound excitonic emission at 358 nm followed by defect-related emission peaks at 363, 371, and 376 nm. The 363 and 376 emission bands are observed upon the coalescence region. The Hall measurements exhibited p-type conduction at 80–300 K (the hole carrier density 6.3×1012 cm−2 and hole mobility 278 cm2/V s at 100 K). The activation energy of the acceptor was estimated to be 60 meV. The possible origin of the p-type conduction is discussed in relation to the unintentionally doped carbon.