a-(Si, Ge):H, F Alloys Prepared from SiH₄ and GeF₄

Abstract

The properties of a-(Si, Ge):H, F alloys prepared by glow discharge deposition from SiH4 and GeF4 are described. The measured IR absorption spectra, sub-gap absorption spectra, dark conduction activation energies, carrier drift mobilities and deep trapping lifetimes of these alloys are similar to those of alloys prepared from SiF4, GeF4, and H2. However, they have over an order of magnitude lower photoconductivity over most of the composition range. Infrared absorption measurements indicate that these alloys have a fluorine content less than 1.5 at.% and a Si-H2 content that increases with germanium concentration.

Low frequency plasma deposition and characterization of Si1−xGex:H,F films

“…The absorption associated with the Ge-F stretch mode is expected to appear in the range of k ¼ 630-650 cm À1 , but it is normally overlapped by the strong Si-H and Ge-H wag mode absorption, as reported in Ref. [8].…”

“…In IR spectra, their behavior with x for the samples deposited with Ar or H 2 dilution in comparison with that reported in Refs. [3,4,8] is analyzed. In the films the appearance of a peak near k ¼ 440 cm À1 is observed, which has not been reported.…”

“…[7] for ECR discharge. GeH 4 is conventionally used as germane source gas and only few works have reported the properties of a-SiGe films prepared from a mixture of SiH 4 and GeF 4 [8,9]. The effect of dilution on the growth and electronic properties has not been systematically studied yet.…”

Hydrogen Reduction of Germanium Tetrafluoride in RF-Discharge

“…The main production method of the above-mentioned structures is a plasma (generated as a rule by different types of RF discharge)-enhanced chemical vapour deposition technology (PECVD). The initial gaseous compounds for silicon are silane SiH 4 and silicon tetrafluoride SiF 4 , while for germanium there are germane GeH 4 , and, less often, germanium tetrafluoride GeF 4 [5,6] though the latter provides for the best photoelectric structure properties [2,7]. The capacitive discharge (110 kHz) PECVD with GeF 4 as the initial substance was also used to grow photosensitive layers of amorphous germanium a-Ge:F for fabrication of uncooled micro-bolometers showing good performance parameters [8,9].…”

Silicon–germanium films prepared from SiH4 and GeF4 by low frequency plasma deposition

“…Many groups have reported the optical, electrical and structural properties of a-SiGe:H produced by different methods including chemical vapor deposition (CVD), plasma enhanced chemical vapor (PECVD), hot-wire (HW) deposition and sputtering. In most investigations the mixture SiH 4 + GeH 4 was used and only few works have reported the properties of alloys prepared from a mixture of SiH 4 and GeF 4 [4,5]. The different studies have demonstrated that the optoelectronic properties of these thin films change significantly with the deposition conditions.…”