Aniosotropies of Nonpolar a-Plane GaN LEDs in Electrical and Optical Properties

Soohwan Janga*, Kwang Hyeon Baikb, Sung-Min Hwangb, S. J. Peartonc, and F. Rend
aDepartment of Chemical Engineering, Dankook University, Yongin, 448-701, Korea
bOptoelectronics Labs, Korea Electronics Technology Institute, Sungnam, Gyeonggi 463-816, Republic of Korea
cDepartment of Materials Science and Engineering, University of Florida, Gainesville, FL 32611
dDepartment of Chemical Engineering, University of Florida, Gainesville, FL 32611
*jangmountain@dankook.ac.kr, tel: 82-31-8005-3623

Keywords: Nonpolar, a-plane GaN, LEDs, BPSF, anisotropy

Abstract

Electrical and optical properties of a-plane GaN on rplane sapphire substrates according to m- and caxes are reported. Ohmic contact resistances were measured using TLM (transfer line method) contacts oriented toward both m - and c-directions of a-plan
GaN. The lowest specific contact resistances of ~10-5 Ωcm2 were obtained when annealed at 700 ℃, and the specific contact resistances increased with temperature after 700 ℃. It is found that the sheet resistance along caxis of a-plane GaN is much higher than the m-axis of aplane GaN. This is due to the carrier scatterings by PSFs (basal plane stacking faults) in the direction perpendicular to the c-axis. A-plane GaN based LEDs aligned to m- and c-axes were fabricated and the output powers of devices for each direction were compared. The
resence of BPSFs significantly influences electrical and optical performances of the devices.

Paper 13.3.pdf