High-purity n-GaAs Research Articles

Magnetophonon Resonance and Fourier Analysis in n-GaAs

With the use of magnetic field modulation technique up to eighteen magneto-phonon peaks are observed in the transverse and longitudinal magnetoresistance of high purity epitaxial n-GaAs. Fourier analysis reveals the second harmonic component resulting in a sharpening of the oscillatory structure in the transverse magnetoresistance and extrema associated with the two LO phonon process in the longitudinal magnetoresistance in addition to the ordinary magnetophonon series. Two methods are described to obtain the damping factor \barγ which is found to be 0.63 from the Fourier analysis and 0.60 from the method described in this paper for the specimen with the highest mobility (1.7 ×10 5 cm 2 /V ·s) at 77 K. The temperature dependence of \barγ for the high purity n-GaAs exhibits a variation T 0.25 at low temperatures, which indicates an importance of the band failing effect for the damping process. The effective mass is determined to be m * =0.0682 m 0 at 77 K.

Hot electrons and exciton-electron collision in GaAs under external electric field

The emission due to free exciton-electron collision has been investigated in relatively high purity n-GaAs under the external electric field. With increasing electric field, the emission peak shifts to lower energy while the higher energy side of the peak broadens. The emission spectra were also compared with the theory. From the higher energy tail, we estimated the electron temperature as a function of the electric field.

Optimization of a tunable far-infrared InSb source

Recombination radiation from Landau states in impact ionized n-InSb provides a magnetically tunable far i.r. source. Investigations in order to optimize the emission intensity and linewidth are performed. The radiation is studied in dependence of the electric and magnetic field the total impurity concentration and the sample geometry. Donor spectroscopy on high purity n-GaAs is demonstrated with a resolution of 3 cm −1.

HIGH-RESOLUTION NUCLEAR RADIATION DETECTORS FROM EPITAXIAL n-GaAs

Surface barrier p-n junction diodes made from high-purity n-GaAs grown by liquid-phase epitaxy, have been operated as α-particle and low-energy γ-ray detectors over the range 77–373°K. Resolutions observed were 1.2 and 2.95 keV (FWHM) at 130 and 295°K, respectively, for 122-keV γ rays and 30 keV for 5.47-MeV α particles. The energy per electron hole pair for α particles is 4.51 eV and the Fano factor for γ rays is ≤0.24 at 130°K.