Study of electrically active defects in n-GaN layer

✍ Scribed by C.B. Soh; D.Z. Chi; A. Ramam; H.F. Lim; S.J. Chua

• Book ID: 104420572
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 319 KB
• Volume: 4
• Category: Article
• ISSN: 1369-8001
• DOI: 10.1016/s1369-8001(02)00025-2

✦ Synopsis

Deep level defects in both p + /n junctions and n-type Schottky GaN diodes are studied using the Fourier transform deep level transient spectroscopy. An electron trap level was detected in the range of energies at E c À E t ¼ 0:2320:27 eV with a capture cross-section of the order of 10 À19 -10 À16 cm 2 for both the p + /n and n-type Schottky GaN diodes. For one set of p + /n diodes with a structure of Au/Pt/p + -GaN/n-GaN/n + -GaN/Ti/Al/Pd/Au and the n-type Schottky diodes, two other common electron traps are found at energy positions, E c À E t ¼ 0:5320:56 eV and 0:7920:82 eV. In addition, an electron trap level with energy position at E c À E t ¼ 1:07 eV and a capture cross-section of s n ¼ 1:6 Â 10 À13 cm 2 are detected for the n-type Schottky diodes. This trap level has not been previously reported in the literature. For the other set of p + /n diodes with a structure of Au/Ni/p + -GaN/n-GaN/n + -GaN/Ti/Al/Pd/Au, a prominent minority carrier (hole) trap level was also identified with an energy position at E t À E v ¼ 0:85 eV and a capture cross-section of s n ¼ 8:1 Â 10 À14 cm 2 . The 0.56 eV electron trap level observed in n-type Schottky diode and the 0.23 eV electron trap level detected in the p + /n diode with Ni/Au contact are attributed to the extended defects based on the observation of logarithmic capture kinetics.