LSA operation of large volume bulk GaAs samples

Peak pulse powers of 350 watts, with 3 percent efficiency at X-band frequencies, were obtained from large volume GaAs devices operating in the LSA mode. Experimental dependence of the LSA mode on circuit loading, applied voltage, and the ratio of carrier concentration to frequency are reported. The results are shown to be in excellent agreement with Copeland's theoretical calculations. The high-current state frequently observed in GaAs samples is shown to result from impact ionization in the high-field portion of dipole domains. A simple expression is derived relating the sample length and carrier concentration to the voltage at which switching to the high-current state occurs. The prevention of high-field domains to permit LSA operation of long samples at high voltages is briefly discussed.