Open AccessFabrication and characterization of GaSb based thermophotovoltaic cells using Zn diffusion from a doped spin-on glass source
Author(s) -
S. Dakshinamurthy,
Smitha Shetty,
Ishwara B. Bhat,
Collin Hitchcock,
R.J. Gutmann,
G.W. Charache,
Mark O. Freeman
Publication year - 1998
Language(s) - English
Resource type - Reports
DOI - 10.2172/307843
Subject(s) - materials science , wafer , common emitter , thermophotovoltaic , optoelectronics , doping , dopant , fabrication , quantum efficiency , etching (microfabrication) , diffusion , analytical chemistry (journal) , secondary ion mass spectrometry , nanotechnology , ion , layer (electronics) , chemistry , medicine , alternative medicine , physics , pathology , thermodynamics , organic chemistry , chromatography
The GaInSb material system is attractive for application in thermophotovoltaic (TPV) cells since its band gap can be tuned to match the radiation of the emitter. At present, most of the TPV cells are fabricated using epitaxial layers and hence are expensive. To reduce the cost, Zn diffusion using elemental vapors in a semi-closed diffusion system is being pursued by several laboratories. In this paper, the authors present studies carried out on Zn diffusion into n-type (Te-doped) GaSb substrates in an open tube diffusion furnace. The dopant precursor was a 2,000 {angstrom} thick, zinc doped spin-on glass. The diffusion was carried out at temperatures ranging from 550 to 600 C, for times from 1 to 10 hours. The diffused layers were characterized by Hall measurements using step-and-repeat etching by anodic oxidation, secondary ion mass spectrometry (SIMS) measurements and TPV device fabrication. For diffusion carried out at 600 C, the junction depth was 0.3 {micro}m, and the hole concentration near the surface was 5 {times} 10{sup 19}/cm{sup 3}. The external quantum efficiency, measured without any anti-reflection coating, of the TPV cells fabricated using mesa-etching had a maximum value of 38%. Masked diffusion was also carried out by opening windows in a Si{sub 3}N{sub 4} coated, GaSb wafer. TPV cells fabricated on these structures had similar quantum efficiency, but lower dark current