Properties of ‘bulk’ GaAsSbN/GaAs for multi-junction solar cell application: Reduction of carbon background concentration

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

“…For the growth of the bulk films of GaAsN, InGaAsN, and GaAsSbN, the reactor pressure was 150 Torr and the growth temperature 600 1C, as measured by an in-situ pyrometer. Previously, we reported that either higher growth temperature or the use of TrisSb antimony precursor, instead of TMSb, gives rise to a significant decrease in the carbon background contamination in GaAsSbN materials [9]. Highresolution X-ray diffraction (HR-XRD) ω -2θ rocking curves around the (004) and (311) reflection for (100) and (311)B substrates, respectively, were used to characterize the out-ofplane lattice constant of the InGaAsN, and GaAsSbN films, which were nominally lattice-matched to GaAs substrates (Δa/ao 0.3%).…”

“…Van der Pauw-Hall measurements were used to determine the background hole concentrations for samples (300 nm-thick) grown on semi-insulating GaAs (100) and (311)B substrates. After thermal annealing treatment, the hole carrier concentration closely matches the carbon acceptor concentration [6,9]. Calibrated secondary ion mass spectroscopy (SIMS) measurements were used on selected samples to determine the actual InGaAsN films composition with 75% errors in the N contents.…”

“…By contrast, N incorporation in InGaAsN grown by MOVPE at low growth temperatures ( $ 530 1C) is rapidly decreased with increasing In concentration [8]. Typically, dilutenitride materials grown by MOVPE have employed low growth temperatures (500-530 1C) for efficient N incorporation, although this brings about higher background carbon impurity concentration [9]. Previous studies on InGaAsN grown by MOVPE at higher growth temperatures (570-650 1C) indicate 1-3% nitrogen incorporation can be achieved with low 10 17 cm À 3 level background carbon content [14,15], although similar studies have not been reported on GaAsSbN grown by MOVPE at such high growth temperatures.…”

“…We previously reported that both Sb and N incorporation into GaAs affect the carbon background impurity concentration reflecting the Sb-C and N-C direct bonding in the MO sources [9]. Bulk GaAsSbN films grown at higher growth temperature were observed to exhibit reduced background carbon contamination [9].…”

The role of photonics in energy

“…[28][29][30] By taking advantage of this progress, the integration of III-V multijunction cells with GaInNAs-containing alloys as one of the cell materials has enabled a record PCE of 43.5%. 31 Other materials including InGaN 32 and InN 33 are currently being pursued, while others such as GaAsBi 34 are being considered for multijunction solar cells. One way of improving the cost-effectiveness of these very expensive but highly efficient solar cells is to use a concentrator, i.e., to harvest light over a large area but deliver it to small but very efficient solar cells 35 (e.g., planar Fresnel lenses 36 ).…”