Production of boron, selenium and lead doped semiconductive alloys and their structural characterization

Semiconductors are one of the most used materials in electronic devices. They are used in many commercial and scientific devices such as solar cells, central processing units, mobile phones, digital music players and lasers. Nowadays, thermoelectric coolers, that are less harmful for the enviroment and more efficient, are one of the interesting research subjects. The most used semiconductor elements in alloys developed in the purpose of using in thermoelectric coolers are elements such as bismuth, tellurium, selenium, antimony. The conductivity of most semiconductors at room temperature is changable with dopant atoms and alloying. In this master thesis, boron, selenium and lead were emloyed, that are commonly used as dopants in alloy manufacturing and dopant atoms? effects on the properties of semiconductor materials were investigated. In experimental study, Sb2Te3 and Bi2Te3 alloy samples with different stoichiometric ratios and dopants were vacuumed in quartz tubes, then melted in continuously moving rotary tube furnace. Samples taken out from the furnace were placed in the crystal growth system and semiconductor alloy production was carried out. Structural and thermal analysis of obtained semiconductor samples were examined by X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and Differential Thermal Analysis-Thermogravimetry (DTA-TG). Finally, semiconductor alloys containing [%75 Sb2Te3 + %25 Bi2Te3] and [%75 Sb2Te3 + %25 Bi2Te3 + %4Te] were produced, dopants of B, Se and Pb were added to these alloys in the ratio of %1, %3 and %5 and structural properties of these alloys were investigated. Produced alloys can be used in researchs for thermoelectric coolers and it can be investigated how the dopants will effect the thermoelectrical performance of these coolers.