Photoluminescence and electrical properties of close space vapor transport GaAs epitaxial layers

Abstract

Close spaced vapor transport (CSVT) epitaxial layers have been grown under water vapor partial pressure p ranging from 5×10−2 to 5 mm Hg for source temperatures of 800 and 850 °C and a substrate temperature of 730 °C, using undoped high-purity GaAs as source material and 〈100〉 chromium doped high-resistivity GaAs as substrate. From Hall measurements, all layers were found to be n-type with a majority carrier concentration in the range of (2–3) ×1017 cm−3 and a mobility 3100–3600 cm2 V−1 s−1 as p varies from 5.0 to 5×10−2 mm Hg. Photoluminescence measurements show the following dominant recombination processes: an exitonic peak at 1.514 eV, a free band acceptor at 1.498 eV, a donor acceptor at 1.490 eV, and two peaks involving complexes at 1.47 and 1.42 eV. These peaks depend on the water vapor pressure: for low values of p only the exitonic peaks exist; as p increases the photoluminescence becomes less efficient until it disappears for p=5.0 mm Hg. This study shows that CSVT-GaAs epilayers grown under proper conditions have high quality and could be used for producing some electronic devices.

Analysis of performance-limiting defects in pn junction GaAs solar cells grown by water-mediated close-spaced vapor transport epitaxy

“…However, while O has been detected in CSVT films at a concentration ~10 16 cm -3 by SIMS [26], the midgap state has only been detected by deep-level transient spectroscopy (DLTS) when O 2 was intentionally introduced into the reactor [27]. Increasing water vapor concentrations during growth have also been correlated with degraded photoluminescence [28] [4], although in our own work with electrochemical cells J sc was only degraded at very high water concentrations (>4000 ppm) [20]. The influence of oxygen on device performance merits further study.…”

Doping of GaAs epitaxial layers grown on (100) GaAs by close-spaced vapor transport

“…GaAs was indeed the first material to be deposited successfully by CSVT. Epitaxial layers were obtained on GaAs (6)(7)(8)(9)(10)(11)(12)(13)(14) and on Ge (1-4, 8, 15, 16) substrates. Their growth mechanisms have been modeled (10,13) and some of their electrical properties (7-9, 13-16) (type of semiconductor, charge carrier densities, and mobilities) as well as their photoluminescence properties (1 1, 12) have been elucidated.…”

Electronic GaAs-on-Silicon Material for Advanced High-Speed Optoelectronic Devices

“…In order to separate material quality issues intrinsic to the CSVT process from those related to heteroepitaxy on silicon, it is useful to compare the data of Table 3 with previously published data for the CSVT growth of GaAs films on GaAs substrates. Using similar process parameters, Mimila-Arroyo et al [65] reported electron mobilities as high as 3600 cm 2 /V-s for samples doped at approximately the same donor concentrations.…”