Mg-doped InN and InGaN - Photoluminescence, capacitance-voltage and thermopower measurements

The bandgap range of InGaN extends from the near-IR (InN, 0.65 eV) to the ultraviolet. To exploit this wide tuning range in light generation and conversion applications, pn junctions are required. The large electron affinity of InN (5.8 eV) leads to preferential formation of native donor defects, resulting in excess electron concentration in the bulk and at surfaces and interfaces. This creates difficulties for p-type doping and/or measuring of the bulk p-type activity. Capacitance-voltage measurements, which deplete the n-type surface inversion layer, have been used to show that Mg is an active acceptor in InN and In_xGa_1-xN for 0.2 < x < 1.0, i.e. over the entire composition range. Mg acceptors can be compensated by irradiation-induced native donors. Thermopower measurements were used to provide definitive evidence that Mg-doped InN has mobile holes between 200 K and 300 K. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.