Growth and characterization of a novel In2Se3 structure

Abstract

Thin films of In 2 Se 3 deposited by thermal co-evaporation crystallize upon vacuum annealing almost single phase into an, up to now, unknown structure. Only when the films are capped with a thin oxide layer before annealing, the reportedly stable ␥-In 2 Se 3 structure, single phase and aligned along the c axis forms. Rutherford backscattering confirms an In to Se ratio of 2 to 3 for both structures. Nevertheless, the new structure has distinct x-ray diffraction peaks and Raman spectra. The new structure has a much lower resistivity than the ␥-In 2 Se 3 structure, consistent with its smaller electrical and optical energy gap. Both structures show large photoconductivity.

Crystal structure of κ-In2Se3

“…Both deposition and post-annealing parameters were varied in order to find optimal conditions for the formation of single phase In 2 Se 3 . In agreement with the previous report [1,2] it was observed that Zn doping during deposition promoted formation of κ-In 2 Se 3 , while air exposure or passivation layer deposition suppressed it. Zn doping allows single-phase κ-In 2 Se 3 to be deposited in polycrystalline form onto substrates heated in the 125 to 250 o C range, while wellannealed undoped films always contained some γ−phase.…”

“…Using this spectrum the 2θ angle for the (005) peak was measured to be 22.33 o , implying c = 1.988 nm. This value agrees very well with the measurement of deGroot and Moodera [1].…”

“…This confirms de Groot's claim that the odd-l peaks of the κ-In 2 Se 3 are more intense in the Xray diffraction pattern [1]. Such unusual line intensity is a manifestation of some symmetry breaking in κ-In 2 Se 3 .…”

“…There are four relatively well-known phases of this compound (α, β, γ, δ) and recently a new κ phase of In 2 Se 3 has been discovered. [1] Still little is known about its properties. Many of the studies performed on In 2 Se 3 have been done on multiphase films, thus preventing a full understanding of its chemical and physical properties.…”

Preparation of indium selenide thin film by electrochemical technique

“…In x Se y is known to have low density of dangling bonds on the layered surfaces which make this material a good choice for application in hetero-junction device structures. This material has undergone many studies [7,[18][19][20] which indicate a lot of difficulties due to the existence of many different phases in a single sample and that is a drawback for this material. Different phases present in the film compete during growth process, and this way both amorphous and poly-crystalline phases are obtained in a single sample.…”