Low-Bandgap Ge and InAsSbP/InAs-Based TPV Cells

摘要

P-GaAs/p-Ge heterostructures with a submicron (0.1μm) GaAs window for the thermophotovoltaic (TPV) application have been fabricated using the combination of LPE and Zn-diffusion techniques. Due to the increase of the open circuit voltage by growth of a GaAs wide bandgap window, an increase of efficiency of Ge based TPV cells from 2.6-4.8% up to 3.1-6.1% takes place for the emitter temperature in the range of 1400-1900 K. The efficiencies higher than 13% under the cut-off at λ < 900 nm AM0 solar spectrum have been achieved in photovoltaic (PV) concentrator cells with a GaAs window layer at photocurrent densities of 3-25 A/cm~2. By means of LPE growth and Zn diffusion techniques, TPV cells based on p-InAsSbP/n-InAsSbP/n-InAs structures were fabricated sensitive in the infrared range of 2.5-3.4 μm. Lattice-matched InAsSbP (Eg = 0.45-0.48eV) quaternary alloy layers were grown on the (100) InAs substrates at 850 K by the step-cooling LPE technique. Low-temperature (600-630 K) pseudo-closed box Zn diffusion was used to produce p-n junctions in InAsSbP and InAs. Developed InAsSbP-based TPV cells demonstrate rather good performance, which can be improved by the structure optimisation.