Ultrasonic Amplification in a Transverse Magnetic Field

概要

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The effects of a transverse magnetic field on the ultrasonic amplification and the velocity of sound in piezoelectric semiconductors are examined in detail by a straightforward extension of White's theory of ultrasonic amplification. It is shown that the magnetic field gives two effects on the characteristics of amplification, i.e., (1) the increase of the threshold electric field for amplification due to dc magnetoresistance and (2) the decrease and increase of the dielectric relaxation frequency and the diffusion frequency, respectively. The calculations are carried out by taking InSb, GaAs, CdS and Te at 77°K as examples. It is found that the transverse magnetic field increases or decreases the amplification factor at a given electric field depending on relative magnitudes of the two effects. It is also found that intrinsic InSb has an action of acoustic low-pass and high-pass filter alternatively with the increase of the magnetic field. The acoustoelectric current oscillation in n-InSb is also briefly discussed.
社団法人応用物理学会の論文
1968-08-05