Effect of Indium Mole Fraction on the Diode Characteristics of ZnO:In/p-Si(111) Heterojunctions

Abstract

We investigated the effect of indium (In) doping (0.6, 1, 5, and 10 at. %) on the diode characteristics of heterostructures consisting of In-doped ZnO films on p-Si(111) substrates. In-doped ZnO films were deposited by pulsed laser deposition with an In-doped ZnO target, and heterojunction diodes were fabricated by photolithography and a lift-off method. The electrical properties of ZnO films were altered by In doping, with the In (10 at. %)-doped ZnO film having the highest electron concentration (3.0×1019 cm-3) and lowest resistivity (1.5×10-2 Ω·cm) of the analyzed ZnO films. In doping also had a strong effect on diode characteristics. In particular, In-doped ZnO/p-Si diodes show a very low reverse current density of approximately 2.8×10-6 A/cm2 (In 10 at. %) at -5 V and a high on–off ratio (In 10 at. %) of about 2.5×10-6 at ±5 V. The heterostructure diodes exhibited typical current–voltage characteristics with turn-on voltages in the range 1.2–2.4 V and series resistances in the range 37–99 Ω. The modified diode characteristics may be related to changes in the ZnO film structure induced by In doping. We also discuss the effect on diode characteristics of In doping of ZnO films.

The Improvement Photoresponsivity of ZnO Based Photodiode with Indium Doping

“…Then, it decreases from from 3% to 10%. The trivalent In can increase the carrier concentration of ZnO because it acts as a donor in ZnO semiconductor layer [8,11]. Therefore, the decrease in barrier height in schottky diodes can be defined by an increase in the carrier concentration depending on In concentration [21].…”

“…Suitable electronegativity and ionic radius, high oxidation resistance and low reactivity of In make it a more attractive dopant to improve photoelectrical performance of ZnO [10]. Also, it has been shown in many studies in the literature that In increases conductivity by increasing the carrier concentration of ZnO [8,11]. The high conductivity and transmittance obtained by In doping in ZnO thin films make it possible to fabricate high-speed photodetectors and transparent electrodes for solar cells [12].…”

“…The presence of intrinsic defects causes the ZnO to exhibit n-type electrical characteristics [8]. Also, the type and carrier concentration of ZnO can be altered with different dopant ions.…”