High-frequency acoustoelectric currents and departures from Ohm's law in thin platelets of CdS I. Linear behaviour

Acoustoelectric interaction in semiconductors

“…If the conditions for round-trip gain are satisfied, the amplified noise will continue to grow with each transit until gain saturation by nonlinear effects becomes effective. This type of amplification was first pointed out by Gurevich and Laikhtman [282] and was studied experimentally by White and Wang [283] and Maines and Paige [284]. Experimental results have been reported for longitudinal, oblique, and transverse waves in CdS [285 to 29013) and to a much less extent in ZnO [291].…”

“…I n all cases thin platelets with plane-parallel surfaces and a thickness of L x 10 to 200 pm have been used. I n the scope of linear theory the amplification factor for round-trip gain is immediately obtained from equation (3.8) using y-= lvd/s and y+ = l + v,/s for the up-stream and downstream wave, respectively [284]. If ambipolar conduction is present, roundtrip gain can be considerably enhanced because net amplification is possible in both directions simultaneously [292] (see also arrows in Fig.…”

Light scattering experiments and nonlinear behaviour of the acoustoelectric oscillator

“…The side faces of the oscillator parallel to the c-axis were polished plane parallel to permit light transmission. At the oscillator faces indium diffused contacts were prepared as described by Maines and Paige [ 5 ] . Light frequency by three filters RF790, RG1000, and RG42.…”

“…The solution of the equation leads to a system of linear algebraic equations of the form -nm+1,1--1 -nrn+i,z+i = 0 3 (5) where m, 1 are integers 0, +1, k2, . , .…”

“…Light scattering has proved to be a very useful tool in studying sound amplification by acoustoelectric (ae) interaction and the development of the ae domains i n semiconducting piezoelectric crystals [2 t o 41. However, rather few attempts have been made to use this technique for studying the development of acoustic flux in photoconducting platelets of the form of ae oscillators as discussed by Maines and Page [5] and by Janus [GI. I n ae oscillators sound amplification is known to occur if the round trip gain condition is satisfied.…”