Far-Infrared Photoconductivity of High Purity n-GaAs in a Magnetic Field Using Rapid-Scan Fourier Transform Spectroscopy.

摘要

The donor impurities in high purity n-GaAs can be described using a hydrogenic model. In a magnetic field the hydrogenic donor levels will split and the chemical shifts of the 1s-2p Zeeman transitions between donor states can be used to identify the impurities. The 1s-2p (m = + or - 1) transitions are the strongest and best to use to identify the impurities. A rapid-scan Fourier transform spectrometer is used in conjunction with gold coated lightguide optics and a 125kG superconducting magnet to obtain photoconductivity spectra. The experimental arrangement and procedure are described in detail. This is the first known use of a rapid-scan Fourier transform spectrometer for this type of experiment. Zero field spectra from a sample with a carrier concentration of 1.25 x 10 to the 14th power/cc and liquid nitrogen mobility of 150,000 sq. cm/V-sec are presented and discussed along with the problems in setting up the experiment and obtaining spectra in a magnetic field.