TY - JOUR
T1 - Non-equilibrium carriers in a-Si:H excited by defect absorption
AU - Saleh, R.
AU - Ulber, I.
AU - Fuhs, W.
AU - Mell, H.
N1 - Funding Information:
1 This work was supported by the Bundesminister mr Forschung und Technolgie (BMFT) under contract number 0328327F. R.S. gratefully acknowledges financial support by P.T.Texmaco Jaya Indonesia.
PY - 1993/12/2
Y1 - 1993/12/2
N2 - We have used light-induced electron spin resonance (LESR) and photoluminescence (PL) to examine the energetic and spatial distribution of non-equilibrium carriers in a-Si:H excited with monochromatic light of 1.16 to 1.96 eV at T = 20 K. The LESR spectra and the observation of intrinsic PL for excitation with hν < 1.4 eV reveal that efficient generation of both electrons and holes occurs by defect absorption. However, the quantum efficiency of the intrinsic PL is smaller by about one order magnitude while that of the defect PL is larger by a factor of 5 compared to excitation with hν > 1.5 eV. This is attributed to the fact that not only carrier creation but also most of the recombination occurs through the defect levels. Our LESR data suggest a very similar ratio of band-tail electrons and holes, namely 0.4, for excitation with 1.16 and 1.96 eV photons, respectively. We believe that this result argues against the existence of a significant density of charged defects in undoped a-Si:H films.
AB - We have used light-induced electron spin resonance (LESR) and photoluminescence (PL) to examine the energetic and spatial distribution of non-equilibrium carriers in a-Si:H excited with monochromatic light of 1.16 to 1.96 eV at T = 20 K. The LESR spectra and the observation of intrinsic PL for excitation with hν < 1.4 eV reveal that efficient generation of both electrons and holes occurs by defect absorption. However, the quantum efficiency of the intrinsic PL is smaller by about one order magnitude while that of the defect PL is larger by a factor of 5 compared to excitation with hν > 1.5 eV. This is attributed to the fact that not only carrier creation but also most of the recombination occurs through the defect levels. Our LESR data suggest a very similar ratio of band-tail electrons and holes, namely 0.4, for excitation with 1.16 and 1.96 eV photons, respectively. We believe that this result argues against the existence of a significant density of charged defects in undoped a-Si:H films.
UR - http://www.scopus.com/inward/record.url?scp=17744416415&partnerID=8YFLogxK
U2 - 10.1016/0022-3093(93)90614-4
DO - 10.1016/0022-3093(93)90614-4
M3 - Article
AN - SCOPUS:17744416415
SN - 0022-3093
VL - 164-166
SP - 563
EP - 566
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
IS - PART 1
ER -