Title :
Enhanced light absorption in GaAs solar cells with internal Bragg reflectors
Author :
Tobin, S.P. ; Vernon, S.M. ; Sanfacon, M.M. ; Mastrovito, A.
Author_Institution :
Spire Corp., Bedford, MA, USA
Abstract :
The use of epitaxial multilayer dielectric mirrors (Bragg reflectors) as back-surface reflectors in thin-film GaAs solar cells on GaAs and silicon substrates is investigated. Al0.3Ga0.9 As/Al0.85Ga0.15As Bragg reflectors were grown by low-pressure MOCVD on GaAs substrates and shown to exhibit near-ideal optical reflectance and excellent structural perfection. Thin GaAs solar cells grown on Bragg reflectors showed increases in short-circuit current (0.5 to 1.0 mA/cm2) and efficiency (0.7 percentage points) relative to cells without back reflectors. Efficiencies of 24.7% at one sun AM 1.5 were measured for GaAs cells only 2 μm thick on Bragg reflectors. In addition to the optical enhancements, Bragg reflectors also appear to improve the defect structure of GaAs-on-Si solar cells. This approach should lead to improved efficiency for GaAs-on-Si solar cells and improved radiation resistance on GaAs cells
Keywords :
III-V semiconductors; gallium arsenide; mirrors; semiconductor thin films; solar cells; 24.7 percent; Al0.3Ga0.9As-Al0.85Ga0.15As; GaAs solar cells; back-surface reflectors; efficiency; epitaxial multilayer dielectric mirrors; internal Bragg reflectors; low-pressure MOCVD; optical enhancements; radiation resistance; semiconductor thin-films; short-circuit current; Absorption; Dielectric substrates; Dielectric thin films; Gallium arsenide; MOCVD; Mirrors; Nonhomogeneous media; Photovoltaic cells; Semiconductor thin films; Silicon;
Conference_Titel :
Photovoltaic Specialists Conference, 1991., Conference Record of the Twenty Second IEEE
Conference_Location :
Las Vegas, NV
Print_ISBN :
0-87942-636-5
DOI :
10.1109/PVSC.1991.169199
