Intrinsic compensation of silicon-doped AlGaN

The silicon doping characteristics of AlxGa1-xN were investigated over the x=0.2-0.5 composition range. A combination of Hall and capacitance-voltage measurements indicated a significant deepening of the Si level, as well as a systematic increase in carrier compensation with increasing compositions. Optical isothermal capacitance transient spectroscopy also revealed the presence of two midgap states with concentrations in the low 10(17) cm(-3) range. The two levels, which are thought to be responsible for the observed compensation, have been assigned to the third and second ionization states of the aluminum vacancy. (C) 2003 American Institute of Physics.