Optical and Transport Properties of p-Type GaAs

Abstract

Electrical properties such as electrical resistivity, Hall coefficient, Hall mobility, carrier concentration of p-type GaAs samples were studied at room temperature (300 K). Resistivity was  found to be of the order of 5.6 × 10^-3?-cm. The Hall coefficient (RH) was calculated to be 7.69 × 10^-1cm³/C and Hall mobility (?_H) was found to be 131cm²/V-s at room temperature from Hall effect   measurements. Carrier concentration was estimated to be 8.12 × 10¹⁸/cm³ and the Fermi level was calculated directly from carrier density data which was 0.33 eV. Photoconductivity measurements  were carried on by varying sample current, light intensity and temperature at constant chopping     frequency 45.60 Hz in all the cases mentioned above. It was observed that within the range of sample current 0.1 - 0.25mA photoconductivity remains almost constant at room temperature 300K and it was found to be varying non-linearly with light intensity within the range 37 - 12780 lux. Photoconductivity was observed to be increasing linearly with temperature between 308 and 428 K. Absorption coefficient (?) of the samples has been studied with variation of wavelength (300 -  2500 nm). The value of optical band gap energy was calculated between 1.34 and 1.41eV for the material from the graph of (?h?)² plotted against photon energy. The value of lattice parameter (a) was found to be 5.651 by implying X-ray diffraction method (XRD).

DOI: http://dx.doi.org/10.3329/jbas.v36i1.10926

Journal of Bangladesh Academy of Sciences, Vol. 36, No. 1, 97-107, 2012