Ultrathin ZnS and ZnO Interfacial Passivation Layers for Atomic-Layer-Deposited HfO₂ Films on InP Substrates

Abstract

Ultrathin ZnS and ZnO films grown by atomic layer deposition (ALD) were employed as interfacial passivation layers (IPLs) for HfO2 films on InP substrates. The interfacial layer growth during the ALD of the HfO2 film was effectively suppressed by the IPLs, resulting in the decrease of electrical thickness, hysteresis, and interface state density. Compared with the ZnO IPL, the ZnS IPL was more effective in reducing the interface state density near the valence band edge. The leakage current density through the film was considerably lowered by the IPLs because the film crystallization was suppressed. Especially for the film with the ZnS IPL, the leakage current density in the low-voltage region was significantly lower than that observed for the film with the ZnO IPL, because the direct tunneling current was suppressed by the higher conduction band offset of ZnS with the InP substrate.

Imaging the influence of oxides on the electrostatic potential of photovoltaic InP nanowires

“…Interestingly, using small amounts of DEZn for compensation doping decreases the lifetime more than heavy p-doping. Though the exact origin is unclear, one explanation could be that outdiffusing Zn forms a thin ZnO layer after exposure to air which has been reported to passivate InP [44]. The same figure includes the measurements performed of the samples with the different passivation schemes.…”

Brief Review of Surface Passivation on III-V Semiconductor

“…ZnS has better thermochemical stability and higher band gap energy than ZnO [36], which makes it an attractive and promising candidate as an interface passivation layer (IPL) material in III-V based devices. Lucero et al used ALD to format a ZnO/ZnS IPL by converting an (NH 4 ) 2 S cleaned p-In 0.53 Ga 0.47 As with diethylzinc and water [37].…”

Barrier reduction and current transport mechanism in Pt/n-InP Schottky diodes using atomic layer deposited ZnO interlayer

“…It was shown in high-k HfO 2 on GaAs that about 2 nm thick ZnO IL could passivate the interface states, especially in the bottom half of the GaAs band gap [23]. About 1.5 nm thick ZnO was also found to act as an effective passivation layer for HfO 2 films on InP substrate [24]. Due to the high electron affinity of ZnO [15], ZnO/semiconductor can provide negative conduction band offset.…”