An Overview of TPV Cell Technologies

摘要

Results of growth, material characterization and device performance of TPV cells based on Ge, Si, InGaAs/InP, GaSb, InGaAsSb, AlGaAsSb, InAsSbP and InAs fabricated by LPE, MOCVD, MBE and diffusion methods are presented. The highest efficiencies have been obtained in TPV cells based on GaSb and InGaAs (lattice matched to InP substrate): external quantum yield as high as 90% in IR-part of photosensitivity spectrum; V_(oc)=0.45-0.52 V; FF=0.7-0.8 at photocurrent densities of 1-5 A/cm~2 and efficiency of more than 10% under available matched radiators. A low-cost Zn-diffusion technology for reproducible fabrication of p-n-GaSb-structures has been developed for producing the high efficiency TPV cells being used for TPV generators. Growth of epitaxial lattice-matched AlGaAsSb wide-bandgap windows and InGaAsSb low-bandgap (0.5-0.6 eV) photoactive layers on GaSb substrates, as well as a fabrication of tandem TPV devices based on GaSb top cells and InGaAsSb bottom cells should allow to improve the GaSb-based cell performance. Another approach for fabrication of the perspective TPV devices with bandgaps of 0.55-0.74 eV has been realized by growth of the lattice-matched and mismatched InGaAs layers on InP substrates. Monolithic interconnected modules (MIMs) fabricated on semi-insulated InP-substrates by the MOCVD method ensure a decrease of the Joule losses and an increase of the sub-bandgap photon reflection in the structures with a back-surface reflector that should contribute to TPV system efficiency owing to photon recirculation. TPV cells based on InAsSbP/InAs are capable to convert radiation with wavelengths up to 2.5-3.5μm and ensure operation with IR emitters heated to lower temperatures.