For the original article see ibid., vol.11, no.9, p.373-5 (1990). The commenters give reasons for the discrepancy between measured and calculated currents for quantum barrier varactors proposed in the above-titled paper, based on the well-known intervalley transfer phenomenon in direct Al/sub x/Ga/sub 1-x/As barriers. Suggestions for improving the Q of the varactors are also included. In their reply, the authors acknowledge the importance of the lowering of the barrier height and briefly discuss some subsequent work. >