A Light-Activated Semiconductor Switch

• Published in: Journal of applied physics Vol. 38; no. 1; pp. 111 - 123
• Main Authors: Meyerhofer, D., Keizer, A. S., Nelson, H.
• Format: Journal Article
• Language: English
• Published: 01.01.1967
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1708939

A GaAs p-n-i-n diode which operates as a light-activated light-coupled switch is described. The i-region is compensated semi-insulating GaAs and is obtained by diffusing Cu, Fe, or Cr into low-doped n-GaAs. The electrical and optical properties of this diode have been studied as well as its switching behavior. The diode exhibits a current-controlled negative resistance region with ratio of off- to on-resistance as high as 106. Turn-on voltages range from 10 to 200 V, and the turn-on time can be made as short as 10 nsec with sufficient overvoltage. The current is limited in the high-resistance mode by intrinsic or one-carrier space-charge-limited conduction in the i region. At higher currents the light emission at the p-n junction causes photoconduction in the i region which is enhanced by the trapping of holes at acceptor levels. In the low-resistance mode all the traps (approximately 1016 cm−3) are filled and remain that way because of the high efficiency of light emission from the junction at the high currents. A model is developed which semiquantitatively describes both the static and dynamic properties of the diode.