In-plane-gate flexible single-crystalline silicon thin-film transistors with high-k gate dielectrics on plastic substrates

Yibo Zhang,Shihui Yu,Kuibo Lan,Guoxuan Qin,Lingxia Li

doi:10.1063/1.5045521

Abstract

Flexible single-crystalline silicon in-plane-gate thin-film transistors (TFTs) with high-k gate dielectrics on plastic substrates have been demonstrated in this letter. The high-k Nb2O5-Bi2O3-MgO (BMN) ceramic has been deposited as gate dielectric layer by magnetron sputtering at room temperature. ∼200 nm Si nanomembrane as the device active layer has been transferred onto the flexible substrates. An in-plane-gate structure has been employed for the flexible TFTs, to achieve high control ability and low leakage current. The flexible TFT demonstrates ∼106 on/off ratio, ∼230 cm2v-1s-1 electron field effect mobility, and only ∼nA leakage current. The capacitances of the in-plane-gate structure are measured and analyzed to better understand the channel control mechanism of the flexible TFTs with high-k gate dielectrics. Mechanical bending tests have been conducted and the underlying mechanism for the device performance variations has been discussed. The flexible TFTs show great potential for the applications in high performance, large area and high integrated flexible circuits.

Highlights

Flexible electronics have attracted wide attentions in the past few years because of their excellent advantages such as bendability, foldability, microminiature and portability.1–5 high performance flexible electronics made from single-crystalline semiconductor materials have been realized and demonstrate a variety of high functionalities in recent years.6–10 These high mechanical and electrical performances make flexible electronics widely desirable in applications such as medical treatment, spaceflight, military and personal wearable devices.11–15 For most of the flexible applications, flexible thin-film transistors (TFTs) are an essential and fundamental element.16–20 for the flexible TFTs up to date, gate dielectrics are most commonly deposited by evaporating SiO or CVD SiOx at low temperatures, which affect the TFTs performance for their low quality and low dielectric constant (
An in-plane-gate structure is employed for these flexible TFTs with high-k gate dielectrics, to achieve high control ability and low leakage current through capacitance couplings
The characteristics of the BMN layer are measured by an Agilent 4285 and the characteristics of the silicon nanomembrane (SiNM)-BMN-ITO heterostructure, in-plane-gate structure and the flexible TFTs were measured by a Keithley 4200 SCS semiconductor characterization system

Summary

INTRODUCTION

Flexible electronics have attracted wide attentions in the past few years because of their excellent advantages such as bendability, foldability, microminiature and portability. high performance flexible electronics made from single-crystalline semiconductor materials have been realized and demonstrate a variety of high functionalities in recent years. These high mechanical and electrical performances make flexible electronics widely desirable in applications such as medical treatment, spaceflight, military and personal wearable devices. For most of the flexible applications, flexible thin-film transistors (TFTs) are an essential and fundamental element. for the flexible TFTs up to date, gate dielectrics are most commonly deposited by evaporating SiO or CVD SiOx at low temperatures, which affect the TFTs performance for their low quality and low dielectric constant (100, has been explored as the gate dielectric layer for flexible TFTs.. High-k ceramic material (Nb2O5-Bi2O3-MgO, BMN), deposited by magnetron sputtering at room temperature with relative dielectric constant >100, has been explored as the gate dielectric layer for flexible TFTs.21 For these flexible TFTs with high-k gate dielectrics, high relative dielectric constant (>100) leads to low breakdown voltage, thereby conventional direct contact gate structures (i.e. top or bottom gates) could limit the fully utilization of these high-k materials as gate dielectrics for flexible electronics. The characteristics of the BMN layer are measured by an Agilent 4285 and the characteristics of the SiNM-BMN-ITO heterostructure, in-plane-gate structure and the flexible TFTs were measured by a Keithley 4200 SCS semiconductor characterization system

AND DISCUSSION

CONCLUSION