Electrical measurements in GaN: Point defects and dislocations

Defects can be conveniently categorized into three types: point, Line, and areal. In GaN, the important point defects are vacancies and interstitials; the line defects are threading dislocations; and the areal defects are sta cking faults. We have used electron irradiation to produce point defects, a nd temperature-dependent Hall-effect (TDH) and deep level transient spectro scopy (DLTS) measurements to study them The TDH investigation has identifie d two paint defects, an 0.06-eV donor and a deep acceptor, thought to be th e N vacancy and interstitial, respectively. The DLTS study has found two po int-defect electron traps, at 0.06 eV and 0.9 eV, respectively; the 0.06-eV trap actually has two components, with different capture kinetics. With re spect to line defects, the DLTS spectrum in as-grown GaN includes an 0.45-e V electron trap, which has the characteristics of a dislocation and the TDH measurements show that threading-edge dislocations are acceptor-like in n- type GaN. Finally, in samples grown by the hydride vapor phase technique, T DH measurements indicate a strongly n-type region at the GaN/Al2O3 interfac e, which may be associated with stacking faults. All of the defects discuss ed above can have an influence on the de and/or ac conductivity of GaN.