Characteristics of ALD-GZO Films with Driven-in Zn and Zn/Mg Sources for the Applications to Optoelectronic Devices

Abstract

In this article, we report on the deposition and characterization of Ga-doped ZnO (GZO) films prepared by thermal-mode (TM) and plasma-mode (PM) atomic layer deposition (ALD) techniques. The GZO films were post-processed by annealing, Zn driven-in, and Mg/Zn driven-in. The driven-in process was performed by rapid thermal diffusion using ZnSiOx or MgSiOx/ZnSiOx spinning-on dopant (SOD) source. The Zn driven-in process on TM-ALD GZO films can effectively alleviate the Zn loss and suppress the increase of resistivity. Furthermore, the Mg/Zn drive-in process of TM-ALD GZO films can effectively enhance the ultraviolet (UV) transmittance. For application to near-infrared region (NIR), the Zn driven-in process on PM-ALD GZO films can increase the carrier concentration and reduce the resistivity. The 380-nm ultraviolet (UV) InGaN/GaN light-emitting diodes (LEDs) with using Mg/Zn driven-in TM-ALD GZO film as a transparent conducting layer can enhance the light extraction from 0.74 to 1.87 mW at 20 mA. Besides, the 2.2-μm InGaAs PIN photodiodes (PDs) with using Zn driven-in PM-ALD GZO film as a window layer can significantly lower the dark current at 1 V from 1.1 × 10−5 (1.4 × 10−3 A/cm2) to 5.2 × 10−6 A (6.6 × 10−4 A/cm2).