Electrical and optical studies on amorphous Se-Te alloys

Abstract

Se1-xTex semiconducting glasses have been prepared and characterized by optical, electrical and X-ray measurements. It is found that homogeneous Se1-xTex glasses can only be prepared, without any trace of detectable crystallinity, up to x approximately=0.30 by the usual conventional quenching technique. Due to the high absorbance of Se1-xTex glasses in the visible region, photoacoustic absorption spectroscopy has been used for the first time to study their optical energy gap variation as a function of x. The optical energy gap Eg of amorphous Se is found to be about 0.12 eV higher than that of c-Se. It is observed that initial small substitution of Te into a-Se rapidly decreases Eg. For x>0.10, the variation in Eg becomes smaller and linear with x. Temperature dependence of the conductivity suggests that the electronic conduction in these glasses takes place via extended states. The activation energy and conductivity prefactor both decrease with x and show sudden changes at x approximately=0.1. An attempt is made to explain these results based on the charge defect model and the tailing of energy bands in the gap region.

The Meyer–Neldel rule for dc activation processes in mixed isoelectronic chalcogens systems

“…This section demonstrates results of σ o versus ΔE for the three considered systems of the mixed isoelectronic chalcogens: the two binaries Se-S [21][22][23][24][25] and Se-Te [26][27][28][29][30], and the ternary Se-S-Te [17,18]. This comprises materials in their non-crystalline phases (bulk glasses, amorphous films and liquids) as well as crystalline ones.…”

Optical properties of Se–Te–Sb thin films

“…Chalcogenide glassy alloys based on amorphous Se have found various applications in different fields, such as: optical recording media because of their excellent laser writer sensitivity [12,13], infrared spectroscopy [14], transistors, detectors [15,16], rectifiers, photocells, switching, memories [17], xerography, and electrographic applications such as photoreceptors in photocopying, laser printing [18], and laser fiber techniques [19][20][21][22]. In the pure state Se has disadvantages because of its short lifetime and low sensitivity [23].…”

Effect of selenium addition on the GeTe phase change memory alloys

“…Se is one of the attractive choices to use as an additive material owing to its flexible amorphous structure and a variety of possible applications in optoelectronics and solar cells [8][9][10]. The Se binary alloys with Te and Ge, have demonstrated improved structural and optical properties [11][12][13][14][15]. Sb x Se 100Àx has found to have low melting temperature and low thermal conductivity with the cost of thermal stability and resistance contrast [6,16].…”