STUDY OF ELECTRICAL PROPERTIES OF ELECTRON DOPED Ge FILM USING GaP AND Sb SOLID SOURCES BY MOLECULAR BEAM EPITAXY METHOD

Abstract

In this work, electrical properties of n-doped Ge epilayers using both GaP and Sb solid sources were investigated. The Ge films were directly deposited on the Si substrate by molecular beam epitaxy method. The resistivity variation of the Ge layers when the growth temperature varies in the range of 140-300^oC and the Sb cell temperature increases from 257^oC to 330^oC was analyzed by four point probe resistivity measurement. Electron mobility and carrier concentration which contributes to the electrically conductive process in the Ge matrix were estimated by Hall measurment. Results shown that, the value of free electron concentration in the Ge film obtained up to 4.1x10¹⁹cm^-3. The band gap narrowing effect of Ge occurs at a high n-doping level was observed from photoluminescence spectra which were recorded at an infrared range of wavelength from 1100nm to 2100nm. Photoluminescence intensity of the n-doped Ge layers was highly enhanced by a factor of 3 times compared to the Ge sample doped with P only.