TY - JOUR
T1 - Effect of Ga doping concentration on the luminescence efficiency of GaN light-emitting diodes with Ga-doped ZnO contacts
AU - Kim, Chang Oh
AU - Kim, Sung
AU - Shin, Dong Hee
AU - Shin, Dong Yeol
AU - Choi, Suk Ho
AU - Hwang, Sung Won
AU - Cha, Nam Goo
AU - Kang, Sammook
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2011-0017373).
PY - 2012/11
Y1 - 2012/11
N2 - P-n junction GaN light-emitting diodes (LEDs) were fabricated using Ga-doped ZnO (GZO) films as electrical contacts and characterized by electroluminescence (EL) and current-voltage (I-V) measurements. GaN p-n epilayers with a total thickness of ~6 μm were grown on c-plane (0001) sapphire substrates by metal-organic chemical vapor deposition. Half region of the p-GaN layer was etched until the n-GaN layer was exposed, and 100-nm-thick GZO contacts were deposited on the p- and n-GaN layers by RF sputtering with varying Ga concentration (n G ) from 1 to 5 mol%. Based on the results of Hall effect, photoluminescence (PL), and X-ray diffraction (XRD), the GZO films were expected to act as best electrical contacts for the LEDs at n G = 2 mol%. Under forward-bias conditions, the I-V curves showed diode characteristics except n G = 5 mol%, and the leakage current was minimized at n G = 2 mol%. Two dominant EL peaks of ultraviolet and yellow emissions were observed at ~376 and ~560 nm, and attributed to near-band-edge- and defect-related radiative transitions, respectively. At n G = 2 mol%, the UV EL showed markedly large intensities for all injection currents, consistent with the results of Hall effect, PL, I-V, and XRD.
AB - P-n junction GaN light-emitting diodes (LEDs) were fabricated using Ga-doped ZnO (GZO) films as electrical contacts and characterized by electroluminescence (EL) and current-voltage (I-V) measurements. GaN p-n epilayers with a total thickness of ~6 μm were grown on c-plane (0001) sapphire substrates by metal-organic chemical vapor deposition. Half region of the p-GaN layer was etched until the n-GaN layer was exposed, and 100-nm-thick GZO contacts were deposited on the p- and n-GaN layers by RF sputtering with varying Ga concentration (n G ) from 1 to 5 mol%. Based on the results of Hall effect, photoluminescence (PL), and X-ray diffraction (XRD), the GZO films were expected to act as best electrical contacts for the LEDs at n G = 2 mol%. Under forward-bias conditions, the I-V curves showed diode characteristics except n G = 5 mol%, and the leakage current was minimized at n G = 2 mol%. Two dominant EL peaks of ultraviolet and yellow emissions were observed at ~376 and ~560 nm, and attributed to near-band-edge- and defect-related radiative transitions, respectively. At n G = 2 mol%, the UV EL showed markedly large intensities for all injection currents, consistent with the results of Hall effect, PL, I-V, and XRD.
UR - http://www.scopus.com/inward/record.url?scp=84869497466&partnerID=8YFLogxK
U2 - 10.1007/s00340-012-5129-z
DO - 10.1007/s00340-012-5129-z
M3 - Article
AN - SCOPUS:84869497466
SN - 0946-2171
VL - 109
SP - 283
EP - 287
JO - Applied Physics B: Lasers and Optics
JF - Applied Physics B: Lasers and Optics
IS - 2
ER -