Chen Jin-Xin, Li Xiao-Xi, Ma Hong-Ping, Huang Wei, Ji Zhi-Gang, Xia Changtai, Lu Hong-Liang, Zhang David Wei
State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics , Fudan University , Shanghai 200433 , China.
Department of Electronics and Electrical Engineering , Liverpool John Moores University , Liverpool L3 3AF , U.K.
ACS Appl Mater Interfaces. 2019 Sep 4;11(35):32127-32134. doi: 10.1021/acsami.9b09166. Epub 2019 Aug 26.
The issue of contacts between the electrode and channel layer is crucial for wide-bandgap semiconductors, especially the β-GaO due to its ultra-large bandgap (4.6-4.9 eV). It affects the device performance greatly and thus needs special attention. In this work, the high-performance β-GaO nanobelt field-effect transistors with Ohmic contact between multilayer metal stack Ti/Al/Ni/Au (30/120/50/50 nm) and unintentionally doped β-GaO channel substrate have been fabricated. The formation mechanism of Ohmic contacts to β-GaO under different annealing temperatures in an N ambient is systematically investigated by X-ray photoelectron spectroscopy. It is revealed that the oxygen vacancies at the interface of β-GaO/intermetallic compounds formed during rapid thermal annealing are believed to induce the good Ohmic contacts with low resistance. The contact resistance () between electrodes and unintentionally doped β-GaO reduces to ∼9.3 Ω mm after annealing. This work points to the importance of contact engineering for future improved β-GaO device performance and lays a solid foundation for the wider application of βGaO in electronics and optoelectronics.
对于宽带隙半导体而言，电极与沟道层之间的接触问题至关重要，特别是对于具有超大带隙（4.6 - 4.9 eV）的β-GaO 。它对器件性能有很大影响，因此需要特别关注。在这项工作中，制备了在多层金属叠层Ti/Al/Ni/Au（30/120/50/50 nm）与非故意掺杂的β-GaO沟道衬底之间具有欧姆接触的高性能β-GaO纳米带场效应晶体管。通过X射线光电子能谱系统地研究了在N气氛中不同退火温度下与β-GaO形成欧姆接触的形成机制。结果表明，快速热退火过程中在β-GaO/金属间化合物界面处形成的氧空位被认为会诱导出具有低电阻的良好欧姆接触。退火后，电极与非故意掺杂的β-GaO之间的接触电阻（）降低至约9.3Ω·mm 。这项工作指出了接触工程对于未来改善β-GaO器件性能的重要性，并为β-GaO在电子学和光电子学中的更广泛应用奠定了坚实的基础。
