Apparatus for determining parameters of semiconductor structures by magnetic quantum effects and admittance spectroscopy

Abstract

A universal combined apparatus is described, which allows investigations of magnetic quantum effects in 3D and 2D semiconductor structures under the influence of optical and microwave radiation on samples in the Faraday and Voight geometries and the recording of the derivatives of the transmission and reflection coefficients of the radiation power under smooth changes in the quantizing magnetic field in a wide temperature range of a studied sample. The vacuum cell of a Janis CCS 400/204N helium cryostat, which is included in the apparatus, has two cold demountable CaF 2 windows that serve for probing IR radiations with different wavelengths. The apparatus provides the determination of the following characteristics: the concen tration and g factor of free charge carriers (FCCs) in semiconductor structures from Shubnikov-De Haas (SDH) oscillation periods and from the positions of the peaks of nonlinear spin resonance curves; the mobil ity and relaxation time of a FCC pulse, from the cyclotron resonance curves with an accuracy of 0.5-1%; and the concentration profiles of FCCs and the parameters of electrically active electron levels and deep cen ters, using the admittance spectroscopy method.