不同退火条件对PEALD制备的Ga2O3薄膜特性的影响

利用等离子增强原子层沉积技术(PEALD)在c面蓝宝石衬底上制备了氧化镓(Ga₂O₃)薄膜,研究了退火气氛(v(N₂)∶v(O₂)=1∶1(体积比)、空气和N₂)及退火时间对Ga₂O₃薄膜晶体结构、表面形貌和光学性质的影响。研究结果表明,退火前的氧化镓处于亚稳态,不同退火气氛下退火后晶体结构发生明显改变,而且退火气氛中N₂比例增加有利于Ga₂O₃重结晶。在N₂气氛下退火达到30 min,薄膜结构已由亚稳态转变成择优取向的β-Ga₂O₃。而且表面形貌分析表明,退火30 min后表面形貌开始趋于稳定,表面晶粒密度不再增加。另外实验样品在 400~800 nm的平均透射率几乎是100%,且光吸收边陡峭。采用N₂气氛退火,对于富氧环境下沉积的Ga₂O₃更利于薄膜表面原子迁移,以及择优取向Ga₂O₃重结晶。     

单晶金刚石p型和n型掺杂的研究

超宽禁带半导体材料金刚石在热导率、载流子迁移率和击穿场强等方面表现出优异的性质,在功率电子学领域具有广阔的应用前景。实现p型和n型导电是制备金刚石半导体器件的基础要求,其中p型金刚石的发展较为成熟,主流的掺杂元素是硼,但在高掺杂时存在空穴迁移率迅速下降的问题;n型金刚石目前主流的掺杂元素是磷,还存在杂质能级深、电离能较大的问题,以及掺杂之后金刚石晶体中的缺陷造成载流子浓度和迁移率都比较低,电阻率难以达到器件的要求。因此制备高质量的p型和n型金刚石成为研究者关注的焦点。本文主要介绍金刚石独特的物理性质,概述化学气相沉积法和离子注入法实现金刚石掺杂的基本原理和参数指标,进而回顾两种方法进行单晶金刚石薄膜p型和n型掺杂的研究进展,系统总结了其面临的问题并对未来方向进行了展望。     

光栅局域调控二维光电探测器

近年来,二维材料独特的物理、化学和电子特性受到了越来越多的科研人员的关注.特别是石墨烯、黑磷和过渡金属硫化物等二维材料具有优良的光电性能和输运性质,使其在下一代光电子器件领域具有广阔的应用前景.本文将主要介绍二维材料在光电探测领域上的应用优势,概述光电探测器的基本原理和参数指标,重点探讨光栅效应与传统光电导效应的区别,以及提高光增益和光响应度的原因和特性,进而回顾光栅局域调控在光电探测器中的最新进展及应用,最后总结该类光电探测器面临的问题及对未来方向的展望.     

Negative photoconductivity in low-dimensional materials

In recent years,low-dimensional materials have received extensive attention in the field of electronics and optoelectronics.Among them,photoelectric devices based on photoconductive effect in low-dimensional materials have a broad development space.In contrast to positive photoconductivity,negative photoconductivity(NPC)refers to a phenomenon that the conductivity decreases under illumination.It has novel application prospects in the field of optoelectronics,memory,and gas detection,etc.In this paper,we review reports about the NPC effect in low-dimensional materials and systematically summarize the mechanisms to form the NPC effect in existing low-dimensional materials.     

Recent advances in two-dimensional layered and non-layered materials hybrid heterostructures

With the development of Moore's law, the future trend of devices will inevitably be shrinking and integration to further achieve size reduction. The emergence of new two-dimensional non-layered materials (2DNLMs) not only enriches the 2D material family to meet future development, but also stimulates the global enthusiasm for basic research and application technologies in the 2D field. Van der Waals (vdW) heterostructures, in which two-dimensional layered materials (2DLMs) are physically stacked layer by layer, can also occur between 2DLMs and 2DNLMs hybrid heterostructures, providing an alternative platform for nanoelectronics and optoelectronic applications. Here, we outline the recent developments of 2DLMs/2DNLMs hybrid heterostructures, with particular emphasis on major advances in synthetic methods and applications. And the categories and crystal structures of 2DLMs and 2DNLMs are also shown. We highlight some promising applications of the heterostructures in electronics, optoelectronics, and catalysis. Finally, we provide conclusions and future prospects in the 2D materials field.