Speaker
Ustun Sunay
(University of Alabama at Birmingham)
Description
Unintentional doping by hydrogen is a concern for industrial growth of p-type GaN which is important in creating blue LEDs and high frequency devices. Using electron paramagnetic resonance (EPR) we investigated hydrogen passivation in p-type nitrides. Samples included conventional GaN and Al_x Ga_{1-x} N(x=0.12,0.28) grown by chemical vapor deposition (CVD) with 1-4x10^{19} cm${-3} Mg and GaN grown by Metal Modulation Epitaxy (MME) yielding 1.5x10^{20} cm^{-3} Mg. The Mg signal was observed during isothermal anneals in N$_{2}$:H_2 (92%: 7%). The Mg EPR signal unexpectedly increased below 600C in GaN, but no changes were observed in AlGaN. The MME Mg EPR signal began decreasing after 10 min at 400C, while the Mg intensity of AlGaN did not start reducing until 500C. As expected the Mg EPR signal in the CVD GaN quenched at 700C, as did the signal in AlGaN. However, the intensity of the Mg signal in MME samples was eliminated after only 20 min at 500C. The different temperature dependence suggests that hydrogen diffusion is affected by increased Mg concentration. These studies are integral for the advancement of p-type GaN.
Co-authors
Jamiyanaa Dashdorj
(University of Alabama at Birmingham)
Mary Zvanut
(University of Alabama at Birmingham)
