No abstract

We have studied the variation of the electron acoustic signal in various materials as a function of the beam accelerating voltage and current. The results show that in most materials examined, e.g. copper, CuZnAl alloy and silicon, it is only the total incident beam power which determines the magnitude of the electron acoustic signal produced. In compensated GaAs the electron acoustic signal depends only on the beam current and is independent of the accelerating voltage which is unlike the case for highly doped GaAs which resembles the metals and silicon. Both semi-insulating and highly doped InP behave as the highly doped GaAs sample. The results are discussed in relation to some of the signal generation mechanisms thought to operate in the electron acoustic (or thermal wave) microscope.