Amorphous thin-film oxide power devices operating beyond bulk single-crystal silicon limit

Yuki Tsuruma,Takashi Sekiya,Gaku Imamura,Genki Yoshikawa,Yoshikazu Nagasaki,Emi Kawashima

doi:10.1038/s41598-021-88222-7

Yuki Tsuruma, Takashi Sekiya + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-88222-7

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Abstract

Power devices (PD) are ubiquitous elements of the modern electronics industry that must satisfy the rigorous and diverse demands for robust power conversion systems that are essential for emerging technologies including Internet of Things (IoT), mobile electronics, and wearable devices. However, conventional PDs based on “bulk” and “single-crystal” semiconductors require high temperature (> 1000 °C) fabrication processing and a thick (typically a few tens to 100 μm) drift layer, thereby preventing their applications to compact devices, where PDs must be fabricated on a heat sensitive and flexible substrate. Here we report next-generation PDs based on “thin-films” of “amorphous” oxide semiconductors with the performance exceeding the silicon limit (a theoretical limit for a PD based on bulk single-crystal silicon). The breakthrough was achieved by the creation of an ideal Schottky interface without Fermi-level pinning at the interface, resulting in low specific on-resistance Ron,sp (< 1 × 10–4 Ω cm2) and high breakdown voltage VBD (~ 100 V). To demonstrate the unprecedented capability of the amorphous thin-film oxide power devices (ATOPs), we successfully fabricated a prototype on a flexible polyimide film, which is not compatible with the fabrication process of bulk single-crystal devices. The ATOP will play a central role in the development of next generation advanced technologies where devices require large area fabrication on flexible substrates and three-dimensional integration.

Highlights

Power devices (PD) are ubiquitous elements of the modern electronics industry that must satisfy the rigorous and diverse demands for robust power conversion systems that are essential for emerging technologies including Internet of Things (IoT), mobile electronics, and wearable devices
The numerical factor related to the efficiency of power conversion, which is critical for PDs, is represented by the figure of merit (FOM) according to the following r elationship[1,4]: FOM = VB2D/Ron,sp, (1)
There have not been any reports of applications to date, amorphous oxide semiconductors (AOS) typically based on indium–gallium–zinc–oxide (InGaZnO)[7,8] are candidates for producing PDs because Schottky barrier diodes (SBDs) with low Ron,sp[9,10,11,12] and high VBD13,14 have been reported for these materials, with the high potential of achieving high FOM

Summary

Introduction

Power devices (PD) are ubiquitous elements of the modern electronics industry that must satisfy the rigorous and diverse demands for robust power conversion systems that are essential for emerging technologies including Internet of Things (IoT), mobile electronics, and wearable devices. Conventional PDs based on “bulk” and “single-crystal” semiconductors require high temperature (> 1000 °C) fabrication processing and a thick (typically a few tens to 100 μm) drift layer, thereby preventing their applications to compact devices, where PDs must be fabricated on a heat sensitive and flexible substrate. PDs based on “amorphous” and “thin-film” materials mitigate both of these problems and enable the fabrication of flexible devices using low temperature processes (Fig. 1 top panel). There have not been any reports of applications to date, amorphous oxide semiconductors (AOS) typically based on indium–gallium–zinc–oxide (InGaZnO)[7,8] are candidates for producing PDs because Schottky barrier diodes (SBDs) with low Ron,sp[9,10,11,12] and high VBD13,14 have been reported for these materials, with the high potential of achieving high FOM. That of the conventional PD: Bulk and epitaxial growth for bulk ingot and single-crystal semiconductor with the bulk substrate, respectively. (c) Material parameters of measured mobility μ and estimated critical breakdown field EC from measured bandgap for amorphous oxide semiconductor materials used in this work, and typical μ and EC for conventional PD materials. (d) PD structures of novel flexible ATOP and conventional rigid discrete

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