Effect of Nitrogen Doping on Threshold Voltage in Amorphous Ga₂Te₃ for Application of Selector Devices

Abstract

The implementation of ultrahigh‐density cross‐point array structures has received considerable interest as emerging storage devices, and threshold switching devices are regarded to be promising as to the suppression of leakage current in cross‐point array structures. Threshold switching devices need to modulate the threshold voltage (Vth) depending on the various memory elements to achieve proper selector device in cross‐point array structures. However, only limited methods are available for controlling Vth. Therefore, the nitrogen (N) doping effects on trap states, density of localized states, and Vth of the amorphous Ga2Te3 (a‐Ga2Te3) selector devices are investigated herein. Furthermore, the electrical conduction behavior is fitted using a trap‐controlled space charge limited conduction mechanism with two transition voltages, i.e., the space charge limited voltage (VSCL) and trap‐filled limited voltage (VTFL). The optical bandgap energy and optical Urbach energy are affected by the N doping in a‐Ga2Te3. In addition, N doping in a‐Ga2Te3 increases the density of localized states. These effects increase both the transition voltages (VSCL and VTFL). Thus, doping a‐Ga2Te3 with N reduces Vth when the trap states are changed. Furthermore, N‐doped a‐Ga2Te3 selector devices exhibit highly reliable switching up to 109 cycles.

Effect of Zr Addition on Threshold Switching Characteristics of Amorphous Ga2Te3 Thin Films

“…The increased V th is considered to be caused by the increased E g opt and the decreased E U opt , which changed the localized states. [ 33,34 ] The increased E a was also consistent with the increased V th . Moreover, the Zr‐doped a‐Ga 2 Te 3 showed the stable endurance characteristics until 10 9 cycles.…”

“…[ 32 ] It is considered that the Zr doping caused the effective energy difference between the conduction edge states and the localized states to be increased with the increased E g opt and decreased E U opt , requiring the larger V th to trigger the threshold switching in the Zr‐doped a‐Ga 2 Te 3 selector device. [ 33,34 ] It was reported that N doping in the a‐Ga 2 Te 3 selector device produced the opposite behavior of V th in our previous work, where V th was decreased with a decrease in E g opt and an increase in E U opt with N doping. [ 34 ] The opposite effect of N and Zr dopants on the shift of V th in the a‐Ga 2 Te 3 selector device suggests the possible modulation of V th by doping.…”

“…[ 33,34 ] It was reported that N doping in the a‐Ga 2 Te 3 selector device produced the opposite behavior of V th in our previous work, where V th was decreased with a decrease in E g opt and an increase in E U opt with N doping. [ 34 ] The opposite effect of N and Zr dopants on the shift of V th in the a‐Ga 2 Te 3 selector device suggests the possible modulation of V th by doping.…”

Tunable Threshold Voltage of ZnTe-Based Ovonic Switching Devices via Isovalent Cation Exchange

“…To successfully utilize these chalcogenide materials in neuromorphic systems as OTS selectors, it has to show promise in tuning the V th to match the purpose of the operating devices . Firstly, we gather previously measured ϵ gap and V th from an extensive literature review. ,,− More details can be found in Table S7. Naively assuming a linear relationship between ϵ gap and V th , as shown in Figure , we propose an empirical linear-like correlation between them.…”

“…Linear empirical model to estimate the threshold voltage ( V th ) as a function of the band gap (ϵ gap ). The circular markers in red, blue, and cyan, and the black diamond marker represent the experimental values obtained from experimental reports. ,− The linear trend lines as obtained from a linear regression for Ge x Se 1– x , Ga 2 Te 3 , and Zn x Te 1– x are shown as purple, cyan, and gray dotted lines, respectively, with the corresponding R 2 values of 0.77, 0.98, and 0.70.…”