Self-rectifying threshold resistive switching based non-volatile memory of CBD/CBD grown vertical n-ZnO nanowire/p-Si heterojunction diodes

Abstract

Vertically oriented ZnO nanowires are grown on p-Si substrate by employing two-step sequential chemical bath deposition technique. The ZnO nanowire exhibits n-type doping due to the presence of oxygen vacancies. The electrical characterizations of n-ZnO NWs/p-Si heterojunction diodes exhibit a self-rectifying, threshold resistive switching behavior. Such switching behavior is explained by oxygen vacancy assisted conducting filament formation mechanism. The relevant charge transport is governed by TC-SCLC and multistep recombination-tunneling processes through the interface traps. Threshold-voltage for resistive switching is observed to be increasing with increasing bias sweep rate. The device shows superior memory endurance for forward and reverse voltage sweep of 50 cycles in fast sweep mode. The ratio of HRS to LRS resistances shows one order of difference. The retention time of such resistive switching memory is recorded to be 4000 seconds, suggesting its non-volatile functionality. Thus, the n-ZnO NWs/p-Si heterojunction can be employed for fabricating promising non-volatile memory devices with excellent endurance and retentions.