Growth of 1‐eV GaNAsSb‐based photovoltaic cell on silicon substrate at different As/Ga beam equivalent pressure ratios

Abstract

We report the performance of 1-eV GaNAsSb-based photovoltaic samples grown on a Si substrate using molecular beam epitaxy at different As/Ga beam equivalent pressure (BEP) ratios. The light current-voltage curve and spectral response of the samples were measured. The sample grown at an As/Ga BEP ratio of 10 showed the highest energy conversion efficiency with an open circuit voltage (V OC ) of 0.529 V and a short circuit current density of 17.0 mA/cm 2 . This measured V OC is the highest ever reported value in GaNAsSb 1-eV photovoltaic cell, resulting in the lowest ever reported E g /q-V OC of 0.50 eV. The increase in the As/Ga BEP ratio also resulted in an increase in the bandgap-voltage offset value (E g /q-V OC ) and a decrease in quantum efficiency up to As/Ga BEP ratio of 18.

Performance of 1 eV GaNAsSb‐based photovoltaic cell on Si substrate at different growth temperatures

“…The reported V OC and J SC values of GaNAsSb PV cells grown on Si/Si–Ge substrate were ≈10% lower than those of the corresponding devices grown on GaAs substrate. Furthermore, GaNAsSb PV cells grown on Si/Si–Ge substrate had comparable E g /q‐V OC values (0.50 eV) to the then‐best 1 eV GaInNAs PV cell (0.49 eV) grown on GaAs substrate . In this study, we report the effects of growth temperature on the performance of four GaNAsSb 1 eV PV cells grown on Si/Si–Ge substrate.…”

Diluted nitride type-II superlattices: Overcoming the difficulties of bulk GaAsSbN in solar cells

“…[10] Such GaInP/GaAs/GaInNAsSb solar cells had an efficiency of 44.0% under concentration, below the theoretical limit, since epitaxial growth and material quality problems inherent to quaternary and quinary dilute nitride alloys seriously affect carrier dynamics. [11] Despite the intense activity of many groups and some relevant advances, [12][13][14][15][16][17][18][19][20][21][22][23][24][25] no improvements in conversion efficiency with three or four-junction cells have been certified since 2015. [1] We have recently proposed that the use of GaAsSb/GaAsN superlattices (SL) might solve these problems.…”

Structures based on GaAs(Sb)(N) semiconductor alloys for high efficiency multi-junction solar cells

“…Indeed, the band structure of GaAs 1-x-y Sb x N y can be modeled by a double BAC (DBAC) model, which is a combination of a CB BAC model for GaAs 1-y N y and a VB BAC model for GaAs 1-x Sb x [68,69]. Moreover, the The GaAs 1-x-y Sb x N y alloy has been recently applied to solar cell technology, both as a thick layer [52,[71][72][73][74][75][76][77][78][79][80][81][82][83][84] and as a capping layer over InAs quantum dots [85,86]. Nevertheless, the obtained solar cell performance is not satisfactory up to now.…”

“…However, as far as we know, the efficiencies achieved have not approached the predicted values, mainly due to difficulties in achieving high-quality material [92]. Several growth optimization strategies to increase the solar cell efficiency are currently under investigation, such as the optimization of V-V [64] or III-V [74] flux ratios, the growth temperature [75], or the use of growth rates higher than 1ML/s, which has been demonstrated to have a positive impact in other N-containing structures [219]. However, seizing on the results obtained in Chapter 4 regarding the possibilities offered by type-II SL engineering, a promising strategy for increasing solar cell efficiency would consist in replacing GaAs 1-x-y Sb x N y bulk layers by GaAs 1-x Sb x /GaAs 1-y N y SLs.…”