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人工晶体学报 ›› 2025, Vol. 54 ›› Issue (6): 997-1004.DOI: 10.16553/j.cnki.issn1000-985x.2025.0002

• 研究论文 • 上一篇    下一篇

Mist-CVD法生长LiGa5O8单晶薄膜及其导电机理研究

赵昊1(), 余博文1, 李琪1, 李光清1, 刘医源1, 林娜1, 李阳1, 穆文祥1, 贾志泰1,2()   

  1. 1.山东大学晶体材料国家重点实验室,新一代半导体材料研究院,济南 250100
    2.山东省工业技术研究院,济南 250100
  • 收稿日期:2025-01-06 出版日期:2025-06-20 发布日期:2025-06-23
  • 通信作者: 贾志泰,博士,教授。E-mail:z.jia@sdu.edu.cn
  • 作者简介:赵昊(2001—),男,山东省人,硕士研究生。E-mail:zh1335390778@163.com
  • 基金资助:
    国家自然科学基金(51932004)

Growth of LiGa5O8 Single Crystal Thin Films and Their Conductive Mechanism by the Mist-CVD Method

ZHAO Hao1(), YU Bowen1, LI Qi1, LI Guangqing1, LIU Yiyuan1, LIN Na1, LI Yang1, MU Wenxiang1, JIA Zhitai1,2()   

  1. 1.The Institute of Novel Semiconductors,State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China
    2.Shandong Research Institute of Industrial Technology,Jinan 250100,China
  • Received:2025-01-06 Online:2025-06-20 Published:2025-06-23

摘要: 宽禁带氧化物半导体普遍存在n型掺杂容易,p型掺杂较为困难的现象。LiGa5O8是一种理论上能够进行双极性掺杂的新型氧化物半导体材料,本文利用雾化学气相沉积(mist-CVD)法生长非故意掺杂的高质量LiGa5O8单晶薄膜,并对薄膜质量、光学、电学等性能进行表征。测试结果发现生长的LiGa5O8薄膜结晶质量较好,厚度为484 nm,表面粗糙度较低(Rq=2.48 nm, Ra=1.73 nm),具有5.22 eV的宽光学带隙;Li、Ga、O元素含量比约为1∶5∶8,薄膜具有n型导电特性。当继续增加Li的比例时薄膜导电性变差,但未具有p型导电特性。利用获得的LiGa5O8薄膜制备光电探测器,发现其在波长254 nm光照下具有良好的I-VI-t特性。通过理论计算富氧条件LiGa5O8中的本征缺陷GaLi和LiGa,发现GaLi缺陷形成能非常低,引入浅的施主能级,从而导致薄膜的n型导电特性;同时当Li的比例增加时GaLi缺陷补偿Li受体,使薄膜几乎不导电。

关键词: 宽禁带氧化物半导体; LiGa5O8单晶薄膜; 雾化学气相沉积法; n型导电; 本征缺陷

Abstract: The phenomenon of facile n-type doping and the challenges associated with p-type doping are frequently observed in wide-bandgap oxide semiconductors. LiGa5O8 is an innovative oxide semiconductor material which is theoretically amenable to bipolar doping. Remarkable properties are exhibited by LiGa5O8, positioning it as a promising candidate in the realm of oxide semiconductor optoelectronics, with the potential to advance the development of high-performance PN homojunctions and other bipolar devices. In this study, unintentionally doped high-quality single crystal LiGa5O8 thin films were synthesized by the mist-chemical vapor deposition (mist-CVD) method, and their quality, optical and electrical properties were meticulously measured and characterized. The experimental results indicate that the synthesized LiGa5O8 thin films exhibit excellent quality and crystallinity, with a thickness of 484 nm, small surface roughness (Rq=2.48 nm, Ra=1.73 nm), and an optical bandgap of 5.22 eV, with a chemical composition ratio of Li, Ga, and O approximately 1∶5∶8. The films are characterized by n-type conductivity, with conductivity diminishing as lithium content increases, while p-type conductivity is not observed. The photodetectors prepared using the obtained LiGa5O8 thin films demonstrate favorable I-V and I-t characteristics under 254 nm illumination. Theoretical calculations of the band structure suggest that achieving p-type doping in LiGa5O8 is more challenging than n-type doping. By analyzing the intrinsic defects GaLi and LiGa in the oxygen-rich conditions of LiGa5O8, it is found that the formation energy of GaLi defects is exceptionally low, introducing shallow donor energy levels, thus resulting in the n-type conductive characteristics of the films; simultaneously, as the proportion of Li increases, GaLi defects compensate for Li acceptors, leading to negligible conductivity in the films. Future endeavors will encompass doping with elements such as Si, Ge and P, with the objective of obtaining higher carrier concentration LiGa5O8 crystal thin film materials.

Key words: wide-bandgap oxide semiconductor; LiGa5O8 single crystal film; mist-CVD method; n-type conduction; intrinsic defect

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