New progress in epitaxial growth of two-dimensional semiconductor single crystal films at wafer level by Peng Hailin group of Peking University

The mainstream silicon-based CMOS (complementary metal oxide semiconductor) technology is facing the limitations of short channel effect and manufacturing cost It is necessary to develop transistor technology based on new materials and new principles to continue Moore's law Due to its ultra-thin planar structure and unique electronic properties, high mobility two-dimensional semiconductor is expected to become an ideal channel material for high-performance electronic devices and digital integrated circuits in the "post Moore era", further reducing the size of transistors and improving their performance In order to meet the demanding requirements of IC Processing Technology and device yield on channel materials, large-area preparation of two-dimensional semiconductor single crystal films is particularly critical and important However, the existing two-dimensional semiconductor material system (transition metal chalcogenide, black phosphorus, etc.) film preparation still does not meet the practical requirements, so it is urgent to achieve a breakthrough in the wafer level two-dimensional semiconductor single crystal film preparation technology Recently, Professor Peng Hailin's research group of School of chemistry and molecular engineering of Peking University aimed at the wafer level single crystal preparation of two-dimensional semiconductor materials, taking the lead in realizing the epitaxial growth of two-dimensional semiconductor (Bi 2O 2 SE) single crystal with high electron mobility, suitable band gap and stable environment Based on the self-designed double temperature chemical vapor deposition system, they used Bi 2O 2SE and perovskite perfect lattice matching and strong interface interaction on the commercial perovskite single crystal substrate [SrTiO 3, LaAlO 3, or (LA, SR) (al, TA) O 3] to promote the same orientation epitaxy and fusion of Bi 2O 2SE crystal core to produce wafer level single crystal film Bi 2O 2SE single crystal thin films exhibit excellent material and electrical uniformity in wafer size, which can be used to construct high performance field effect transistors in batches The standard top gate FET based on the two-dimensional bi2o2se single crystal thin film exhibits high room temperature apparent mobility (> 150 cm 2 / VS), high current switching ratio (> 105) and high open state current (45 μ A / μ m) Relevant achievements were published in nano letters (wafer scale growth of single crystal 2D semiconductor on perovskite oxides for high performance translators Nano letter 2019, 19, 2148) Professor Peng Hailin of Peking University is the corresponding author of the work The first author is tan Congwei, a doctoral student of Peking University Figure 1: epitaxial growth and field effect transistors (source: nano lett.) of wafer level Bi 2O 2SE single crystal films Recently, Peng Hailin's research team used the wafer level oxide molecular beam epitaxy system (MBE) to precisely control the ratio of Bi / SE / O high vapor pressure multicomponent and substrate growth temperature, and achieved the atomic level thickness of Bi 2O 2SE The MBE epitaxial growth of single crystal thin films and the electronic band structure of single cell (1-uc) thick two-dimensional Bi 2O 2SE thin films were first analyzed by using angle resolved photoelectron spectroscopy (ARPES) The results show that the two-dimensional Bi 2O 2SE with single crystal cell thickness has a low electron effective mass of about 0.15m 0 and a band gap of about 0.8ev, which proves that the ultra-thin Bi 2O 2SE with single crystal cell thickness is still a semiconductor material with high mobility and has potential application in short channel devices in the future The preparation of two-dimensional Bi 2O 2SE single crystal thin film at wafer level makes up the blank of high mobility two-dimensional semiconductor single crystal wafer material, and provides the material basis for the exploration of new high-speed and low-power electronic devices in the post Moore era, which has important basic scientific significance and application value The above related achievements were published in advanced materials (molecular beam epoxy and electronic structure of atomically thin oxyselenide films, DOI: 10.1002/adma.201901964) Professor Peng Hailin of Peking University and researcher Guo Jiandong of the Institute of physics of the Chinese Academy of sciences are the co authors of this work The first authors are Liang Yan, postdoctoral student of Boya of Peking University and Chen Yujie, doctoral student of Tsinghua University This series of work has been funded by the Ministry of science and technology and the National Natural Science Foundation of China The partners include Gao Peng, researcher Chen Jianhao, Professor Wang Yong, Zhejiang University, Professor Yuan Hongtao, Nanjing University, Associate Professor Yang Lexian, Tsinghua University, and Professor Chen Yulin, Oxford University Figure 2: epitaxial growth and electronic structure analysis of Bi 2O 2 se film with atomic thickness (source: Advanced Materials)