Handbook of thin film technology

Investigation of the switching phenomenon in TlInSeS single crystals revealed that its behaviour is typical of a memory switch. The switching process occurs symmetrically which, means it takes place with both polarities on the crystal. The current–voltage characteristics (CVC) of symmetrical Ag–TlInSeS–Ag structures exhibit two distinct regions: a high-resistance OFF-state and a low-resistance ON-state that has negative differential resistance (NDR). TlInSeS is a quaternary semiconductor that exhibits S-type CVC. The experimental results indicate that the switching phenomenon in our sample is very sensitive to temperature, illumination dose, and sample thickness. The switching parameters were observed under various ambient conditions. The present study is the first investigation of the switching phenomenon in TlInSeS. The data are presented alongside full theoretical curves that are drawn as guides for the eye.

Negative Resistance and Memory Effects in TlInSeS Single Crystals

Crystallized thin films of layered semiconductor GaTe were fabricated on silica glass by RF magnetron sputtering in H2 and Ar atmospheres. The structure and optical characteristics of these GaTe films were investigated by X-ray diffraction, atomic force microscope measurements and UV-Vis spectrophotometer measurements. The XRD patterns of the films deposited at substrate temperature up to 600°C in argon gas only showed an amorphours structure. The films fabricated with an H2 and Ar gas mixture were crystallized at a hydrogen mole fraction of more than 1 mol.%. Crystallinity and the orientation of the crystalline films showed a dependence on the hydrogen mole fraction. The photo absorption edges showed a direct transition with an optical gap of 1.57 eV, which was in good agreement with that of single GaTe crystals (1.66 eV). The processes of film deposition and crystallization were strongly affected by the presence of hydrogen.

Film Structure and Photo Absorption Spectrum of Crystalline GaTe Thin Films Growth by Radio-frequency Magnetron Sputtering Method

Different thickness thin films of the ternary alloy Ga5Se20Te75 have been vacuum deposited on clean glass substrates held at room temperature at a very fast rate. The film resistance has been measured as a function of temperature during two cycles of heating and cooling. It has been found that the resistance‐temperature (R‐T) variation of the films during first heating and cooling is different, the R‐T curve during heating lying above the R‐T curve during cooling in the case of thinner films and below in the case of thicker films. There are two possible explanations for the difference in resistance variation during heating and cooling and between the thinner and thicker films. The first is due to the semiconducting nature of the material and the second is due to the removal of frozen‐in defects and/or change in concentration depth profile. In addition to these, the phenomenon of self‐annealing can also take place in thicker films. Log resistance vs reciprocal temperature plots are found to be linear, indi...

A. Bhaskaran

Papers

Electrical conduction in ternary semiconductor Ga5Se20Te75 thin films