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29 October 2001 Identification of deep levels in π-GaN epilayers
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Proceedings Volume 4594, Design, Fabrication, and Characterization of Photonic Devices II; (2001)
Event: International Symposium on Photonics and Applications, 2001, Singapore, Singapore
In this paper, the deep level defects in (pi)-GaN Schottky and the p/(pi)GaN diodes have been studied using digital deep level transient spectroscopy (DLTS). The alternative isothermal technique offered by the DL8000 system is used in complement to conventional temperature scan technique. Electron trap levels at Ec -Et ~ (0.23 - 0.27 eV) are detected for p/(pi) diode and (pi)-type Schottky diodes by both techniques. Although similar activation energy is obtained, it appears that the traps are associated with different defects, based on the observation of different capture cross-sections (10-16cm2 for (pi)-type Schottky and 10-19cm2 for p/(pi) diodes) and different capture kinetics (exponential for (pi)-type Schottky and logarithmic for p/(pi) diodes). In addition, three other electron traps are found for the (pi)-type Schottky diode at higher temperatures with Ec -Et ~ 0.56 eV, Ec -Et ~ 0.82 eV and Ec-Et~ 1.07 eV. The Ec -Et ~ 0.56 eV and Ec -Et ~ 0.82 eV traps in (pi)-type Schottky and the Ec -Et ~ 0.23 eV trap level in p/(pi)diode are attributed to extended defects. For the p /(pi) diode, a minority carrier (hole) trap level is also identified under minority carrier injection, with an energy position at Et -Ev ~ 0.85eV and a capture cross-section of 8.129x10-14 cm2. This level might be related to the same defects that gives rise to yellow luminescence detected in (pi)-GaN layer.
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Chew Beng Soh, Dong Zhi Chi, Hui Fern Lim, and Soo-Jin Chua "Identification of deep levels in π-GaN epilayers", Proc. SPIE 4594, Design, Fabrication, and Characterization of Photonic Devices II, (29 October 2001);

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