High thin-film yield achieved at small substrate separation in chemical bath deposition of semiconductor thin films

A technique to improve thin-film yield in chemical bath deposition of semiconductor thin films is presented. This involves the use of very small substrate separation, 0.1 mm., to eliminate the passive layer of the bath, which contributes solely to precipitation. At small substrate separation, a thin layer of the bath mixture is held by surface tension between pairs of substrates. The thin-film yield, which is the percentage of the metal ions in the bath utilized towards the film formation, obtained in this experimental set-up is considered to be near 100% for CuS, Cu2-xSe, US and CdSe thin films. The final thickness estimated for the films is about 40-50 nm. The optical and electrical properties of these films are presented to illustrate that at such film thickness they fulfil the requirements for certain applications.