Growth parameters effect on the electric and thermoelectric characteristics of Bi2Se3 thin films grown by MOCVD system

Bi2Se3 thin films were grown by metal organic chemical vapour deposition (MOCVD) on pyrex substrate in an horizontal reactor using Trimethylbismuth (TMBi) and Diethylselinium (DESe) as metal-organic sources. The effect of the growth parameters such as substrate temperature, T-g, and TMBi partial pressure, P-TMBi, on the structural, electrical and thermoelectrical properties of Bi2Se3 films, has been investigated. We noticed that a high growth temperature is very important for a good orientation of crystallites, which can be directly related to the best values of Hall mobility and Seebeck coefficient found. Therefore, a large stability of the reactions over the substrates with following growth conditions: 455degreesCless than or equal toT(g)less than or equal to485degreesC, 0.5 x 10(-4) less than or equal to P-TMBi less than or equal to 1 x 10(-4)atm and a total hydrogen flow rate D-T = 3 slm, is achieved. In these optimal growth conditions, we found a better crystalline structure of Bi2Se3 thin films using X-ray diffraction. Thus, these layers always displayed n-type conduction using Hall effect, with carrier concentration close to 2 x 10(19) cm(-3) and maximum values of Hall mobility and Seebeck coefficient of mu = 247 cm(2)/Vs and \alpha\ = 120 muV/K respectively. Then, these films appear to be very promising for thermoelectric applications. (C) 2002 Elsevier Science B.V. All rights reserved.