Deep levels in undoped and weakly Mg-doped n-type GaN films fabricated by metalorganic chemical vapor deposition were examined with deep level transient spectroscopy. Deep levels measured at 0.26 and 0.62 eV below the conduction band were found in relatively low concentrations of ∼2×1013 cm−3 in undoped GaN. Addition of small quantities of the Mg acceptor species by means of bis-cyclopentadienyl magnesium (Cp2Mg) during growth corresponded to a significant increase in the concentration of the level at 0.62 eV. The concentration of the shallower level, found to be independent of the Cp2Mg addition, remained unchanged. These deep levels may detrimentally affect optical and electrical properties when fabricating p-type GaN.

Electrical transport properties of Mg-doped p-GaN grown by organometallic vapor phase epitaxy were studied between 100 and 700 K. Calculations using Fermi-Dirac statistigs were carried out, identifying the majority carrier to be holes over the whole temperature range considered. The acceptor level is 0.17 ± 0.01 eV. The hole mobility is 10 cm2/V·s and is almost temperature independent from 160 to 300 K. The detailed analysis employing Fermi-Dirac statistics was then extended to determine the temperature dependence of the Fermi level.

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Schottky barrier diodes of Au-n-Al0.14Ga0.86N grown by Organometallic Vapor Phase Epitaxy were obtained and characterized between 77 K and 373 K. Under forward bias the value of the ideality parameter n=1.41 and the threshold voltage is 0.75 V. The reverse bias leak current is below 10-10 A on a reverse bias of 10 V. The barrier height (Φ B) was determined to be (1.17±0.03) eV and (1.3±0.05) eV by the current-voltage and the capacitance-voltage measurement repectively.