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Impurity concentrations detected by SIMS in m-plane GaN samples grown under different V/III ratios plotted along with the net n-type doping concentration measured by C-V analysis (square symbols). A strong correlation between background oxygen and background doping is clear, with a monotonic dependence on V/III ratio.
(a)-(c) DLTS spectra of the 80 s−1 rate window for m-plane GaN samples grown with V/III ratios of 400, 1000, and 2500. The solid and dashed lines were the results of fitting the experimental data with multiple Gaussian peaks, which revealed that the DLTS peak around 120 K in the highest V/III ratio sample actually consisted of two electron traps. Activation energies and individual concentrations (in cm−3) for each electron trap are listed. (d) Arrhenius plots for each deep level.
Concentrations of the traps present at EC − 0.14 eV, EC − 0.21 eV, and EC − 0.67 eV are plotted for each V/III ratio as a function of oxygen impurity concentration measured by SIMS. The dashed lines are meant to demonstrate the trends more clearly.
Room temperature steady state photocapacitance spectra of m-plane GaN grown with different V/III ratios. The traps are identified with the SSPC onset energies as shown, and trap concentrations are calculated from the corresponding step heights.
Summary of SIMS result and deep level concentrations in m-plane GaN films grown by NH3-MBE with different V/III ratios. All impurity and trap concentrations given in cm−3.
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