GaAs and Ga1-xAlxAs light-emitting devices with light-activated negative resistance

New GaAs and Ga1-xAlxAs electroluminescent ("LANER") diodes have been developed that exhibit light-activated negative resistance. Room-temperature switching operation is possible. In the case of the GaAs device, the p-n-p-n structure was fabricated by liquid epitaxy, using Si as an amphoteric dopant. This multilayer structure was prepared in one growth process by varying the cooling rate, typically from 0.5° C/rain to 14° C/min. The p-n-p-n structure was examined by measuring both photovoltaic effects and the I-V characteristics. Breakdown can be triggered by light or by increasing voltage, similar to the behavior of an SCR. The turnover voltage Vt, in this diode is typically 15 V at room temperature. Vtdecreases with decreasing temperature and with increasing irradiation intensity. The current flowing through the diode is less than 0.1 mA below Vt. In the high-conductivity state, radiation with a peak at 9400 Å is emitted, with an external efficiency of about 5%. Switching times of 0.25 µs are attained at higher applied voltage.