Narrow band gap (1 eV) InGaAsSbN solar cells grown by metalorganic vapor phase epitaxy

Abstract

Heterojunction solar cell structures employing InGaAsSbN (Eg ∼ 1 eV) base regions are grown lattice-matched to GaAs substrates using metalorganic vapor phase epitaxy. Room temperature (RT) photoluminescence (PL) measurements indicate a peak spectral emission at 1.04 eV and carrier lifetimes of 471–576 ps are measured at RT from these structures using time-resolved PL techniques. Fabricated devices without anti-reflection coating demonstrate a peak efficiency of 4.58% under AM1.5 direct illumination. Solar cells with a 250 nm-thick InGaAsSbN base layer exhibit a 17% improvement in open circuit voltage (Voc), 14% improvement in fill factor, and 12% improvement in efficiency over the cells with a thicker (500 nm-thick) base layer.

1.25-eV GaAsSbN/Ge Double-Junction Solar Cell Grown by Metalorganic Vapor Phase Epitaxy for High Efficiency Multijunction Solar Cell Application

“…We previously reported that the unintentional carbon background doping of GaAsSbN could be minimized by higher growth temperatures and through the use of alternative gallium and antimony MO sources [7]. Through such growth optimization, the background carbon concentration in MOVPE-grown GaAsSbN bulk materials is reduced by two orders of magnitude over that of previously reported InGaAsSbN materials (1 × 10 19 cm −3 ) [9]. The achievement of GaAsSbN material with low background carbon contamination allows for counter-doping with Si to produce highly n-type GaAsSbN needed for a homojunction device.…”

Variable temperature carrier dynamics in bulk (In)GaAsNSb materials grown by MOVPE for multi-junction solar cells

“…Thermal annealing was performed in the MOVPE reactor for some samples. A two stage annealing process was employed as reported in our previous publications [3,4]. Some of our dilute nitride samples were also annealed using RTA.…”

“…Understanding carrier dynamics in these materials is crucial in optimizing material growth, but only a small number of groups have reported carrier lifetimes of MBE-grown bulk InGaAsNSb materials [2] and of bulk InGaAsNSb materials grown by MOVPE [3,4]. It is well known that MOVPE is a preferred technique in producing multi-junction solar cells based on III-V materials.…”

Impact of growth temperature and substrate orientation on dilute-nitride-antimonide materials grown by MOVPE for multi-junction solar cell application

“…Dilute-nitride materials grown by MBE generally have very low background carrier concentrations ( $ 1 Â 10 15 cm À 3 ). By contrast, high density of background carbon impurities, which correlates with poor luminescence properties and short minority carrier diffusion length, is a challenging issue for MOVPEgrown dilute-nitride-antimonide materials [4,6]. Unintentional carbon incorporation is aggravated by the low growth temperatures generally employed to achieve efficient N incorporation.…”

“…Ideally, all subcells would be grown monolithically by employing materials lattice-matched to the substrate. Multinary bulk films of dilute-nitride materials possessing a narrow energy band gap (E g $ 1 eV), such as GaAsN, InGaAsN, GaAsSbN, and InGaAsSbN, are very attractive to employ for III-V multi-junction solar cell owing to the ease of bandgap energy tuning and lattice matching to GaAs with a small amount of N. There are several prior successful achievements of single junction solar cell employing dilute-nitride materials grown by molecular beam epitaxy (MBE) [2,3] and metalorganic vapor phase epitaxy (MOVPE) [4,5]. Dilute-nitride materials grown by MBE generally have very low background carrier concentrations ( $ 1 Â 10 15 cm À 3 ).…”