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Etchant for chemical thinning of InP and its application in the fabrication of InP diffused junction solar cells
Author(s) -
Faur Mircea,
Faur Maria,
Jayne D. T.,
Bailey S.,
Goradia M.
Publication year - 1994
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740210208
Subject(s) - passivation , layer (electronics) , materials science , etching (microfabrication) , isotropic etching , common emitter , oxide , diffusion , p–n junction , fabrication , thinning , analytical chemistry (journal) , mineralogy , nanotechnology , optoelectronics , chemistry , metallurgy , medicine , ecology , physics , alternative medicine , pathology , chromatography , biology , thermodynamics
A new etchant, which we have called ‘PNP’, with the composition ( o ‐H 3 PO 4 ) u : (HNO 3 ) v : (H 2 O)( 2 ) t : (H 2 O) 100−( u + v + t ) has been developed for thinning, after contacting, the n + and p + emitter layer of n + p and p + n InP structures made by thermal diffusion. By varying u , v and t , reproducible etch rates of 5–10 nm min −1 have been obtained. After thinning the 2.5–4.5 μm thick p + InP layer down to 60–250 nm, specular surfaces have been obtained at up to 80 nm min −1 etch rates. Owing to its intrinsic qualities, the residual phosphorus‐rich oxide after thinning the emitter layer provides surface passivation of p + InP surfaces and can also serve as a first‐layer antireflective coating. Very high quality p + n InP structures were also obtained using a thin (30–40 Å thick) phosphorus‐rich chemical oxide, grown using this etchant as a diffusion cap layer.