Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 5: Nitrides: mostly transport properties and recombination processes

HL 5.4: Vortrag

Montag, 31. März 2014, 10:15–10:30, POT 251

Formation of Schottky contacts on n-type GaN bulk crystals grown by hydride vapor phase epitaxy (HVPE) — •Ronald Stübner1, Vladimir Kolkovsky1, Jörg Weber1, Gunnar Leibiger2, and Frank Habel21Technische Universität Dresden, 01062 Dresden, Germany — 2Freiberger Compound Materials GmbH, 09599 Freiberg, Germany

In the present study we investigate the formation of Schottky contacts on GaN grown by hydride vapor phase epitaxy (HVPE). Evaporated silver exhibits good rectifying contacts with leakage currents of about 10−5 A cm−2 and a rectification ratio of about 2000 on as-grown n-type GaN for small growth ratios between N and Ga. Contacts have no rectifying behavior in samples grown at a higher ratio of N/Ga. We correlate these observations with the presence of negatively charged gallium vacancies in our samples. They compensate the positively charged donors and lead to a significant increase in series resistance. Deep level transient spectroscopy studies reveal two deep level defects E250 and E610 in our samples. The results are consistent with the previous assignment of E250 to a defect containing a gallium-vacancy [1] and E610, which was attributed to the nitrogen antisite [2]. [1] Z.-Q. Fang et al. Appl. Phys. Lett. 78, 332 (2001). [2] P. Hacke et al., J. Appl. Phys. 76, 304 (1994).

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