Comparison of a dominant electron trap in n-type and p-type GaNAs using deep-level transient spectroscopy

Abstract

Both p-type and n-type dilute-nitrogen GaNAs epitaxial layers grown by metal-organic chemical vapor deposition were characterized by deep-level transient spectroscopy (DLTS). For each case, the dominant DLTS signal corresponds to an electron trap having an activation energy of about 0.2–0.3 eV for p-type GaNAs and about 0.3–0.4 eV for n-type GaNAs. In p-type GaNAs, the electron traps fill slowly, as the DLTS signal reaches saturation using zero-bias filling pulses with widths of 1 s. The electron traps fill quickly in the n-type GaNAs, as the DLTS signal does not typically increase after the shortest fill time of 10μs. The electron-trap densities are calculated using modeling that accounts for the spatial region where traps fill and emit during DLTS measurement. A set of p-type samples with mid-1016cm−3 net acceptors has N content ranging from 0.02% to 1.2%, and the resulting electron-trap concentrations range from 1.4×1017 to 4.3×1017cm−3. A set of n-type samples with mid-1017cm−3 doping has N content ra...