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Deep level defects in dilute GaAsBi alloys grown under intense UV illumination

Journal Article · · Semiconductor Science and Technology
Dilute GaAs1-xBix alloys exhibiting narrow band edge photoluminescence (PL) were recently grown by molecular beam epitaxy (MBE) with the growth surface illuminated by intense UV radiation. To investigate whether the improved optical quality of these films results from a reduction in the concentration of deep level defects, p+/n and n+/p junction diodes were fabricated on both the illuminated and dark areas of several samples. Deep Level Transient Spectroscopy (DLTS) measurements show that the illuminated and dark areas of both the n- and p-type GaAs1-xBix epi-layers have similar concentrations of near mid-gap electron and hole traps, in the 1015 cm-3 range. Thus the improved PL spectra cannot be explained by a reduction in non-radiative recombination at deep level defects. We note that carrier freeze-out above 35 K is significantly reduced in the illuminated areas of the p-type GaAs1-xBix layers compared to the dark areas, allowing the first DLTS measurements of defect energy levels close to the valence band edge. These defect levels may account for differences in the PL spectra from the illuminated and dark areas of un-doped layers with a similar Bi fraction.
Research Organization:
NREL (National Renewable Energy Laboratory (NREL), Golden, CO (United States))
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1329997
Report Number(s):
NREL/JA-5K00-67319
Journal Information:
Semiconductor Science and Technology, Journal Name: Semiconductor Science and Technology Journal Issue: 8 Vol. 31; ISSN 0268-1242
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English

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