Photocontrolled double-barrier resonant-tunneling diode  H. s. Li, Y. W. Chen, K. l. Wang, D. S. Pan, L. P. Chen, and J. M. Liu  Department of Electrical Engineering, University l!f California-Los Angeles. Los Angeles.  California 90024-1594  (Received 13 September 1993; accepted 15 September 1993)