Incorporation of Carbon in Free-Standing HVPE-Grown GaN Substrates

摘要

Carbon doping is a viable approach for compensating the unintentional donors in GaN and achieving semi-insulating substrates necessary for high-frequency, high-power devices. In this work, bulk material properties and point defects are studied in mm-thick free-standing carbon-doped GaN to understand the efficacy of the carbon dopant. Temperature-dependent Hall measurements reveal high resistivity and low carrier concentrations at temperatures as high as 560 degrees C in a 6x10(17)cm(-3) C-doped sample, and electron paramagnetic resonance (EPR) indicates that carbon acts as the compensating defect. Photoluminescence, in agreement with photo-EPR, suggests that the compensating center is C-N; however, additional defects, which possibly limit compensation, are formed at carbon concentrations greater than 5x10(17)cm(-3).