A new binary phase in the tin monoselenide system: chemical epitaxy of orthorhombic γ-SnSe thin films

A new orthorhombic binary phase in the tin mono-selenide system, γ-SnSe, was deposited from solution onto an intermediate layer of PbS on GaAs substrates. Its structure is based on orthorhombic lead telluride (PbTe) which was reported to exist at high pressures, yet has never been observed in SnSe. The proposed model of γ-SnSe was experimentally determined using X-ray diffraction with lattice parameters a 0 = 0.8332 nm, b 0 = 0.4136 nm, c 0 = 0.6115 nm, R p = 5.96, and R wp = 8.16. The films show heteroepitaxial relations with the underlying layer of PbS. Deposition of SnSe from alkaline solution resulted in a new binary phase of tin monoselenide, γ-SnSe. TEM and electron diffraction showed that growth on PbS substrates resulted in epitaxial monoselenide films.