Open AccessCarrier extraction from GaSb quantum rings in GaAs solar cells using direct laser excitation
Author(s) -
James Juanita Saroj,
Fujita Hiromi,
Carrington Peter J.,
Marshall Andrew R.J.,
Krier Anthony
Publication year - 2014
Publication title -
iet optoelectronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.379
H-Index - 42
eISSN - 1751-8776
pISSN - 1751-8768
DOI - 10.1049/iet-opt.2013.0062
Subject(s) - photocurrent , solar cell , optoelectronics , materials science , excitation , band gap , quantum efficiency , laser , excited state , atomic physics , optics , physics , quantum mechanics
The authors report on the analysis of the hole escape mechanisms from type‐II GaSb quantum rings (QRs) embedded within the active region of a GaAs single junction solar cell. When the solar cell is excited by using a 1064 nm infrared laser with excitation energy lower than the bandgap of the GaAs matrix, photogenerated electron–hole pairs are created directly within the GaSb QRs. The QR photocurrent exhibits a linear dependence on the excitation intensity over several decades. The thermal activation energy was found to be weakly dependent on the incident light level and increased by only a few meV over several orders of excitation intensity. The magnitude of the relative absorption in the author's QRs when directly probed by using a 1064 nm laser with an incident power density of ∼ 2.6 W cm −2 is found to be ∼ 1.4 × 10 −4 per layer. The thermal escape rate of the holes was calculated and found to be ∼ 10 11 to 10 12 s −1 , which is much faster than the radiative recombination rate 10 9 s −1 . This behaviour is promising for concentrator solar cell development and has the potential to increase solar cell efficiency under a strong solar concentration.