Heterojunction field-effect transistors based on the β-(Al_xGa_1−x)₂O₃/Ga₂O₃ heterostructure grown by ozone-assisted molecular beam epitaxy were demonstrated for the first time. Al composition ratios in the 14%–23% range were validated using x-ray diffraction on the three samples grown for this study. Electrochemical capacitance-voltage (ECV) measurements showed the presence of a charge sheet in the delta-doped (Al_xGa_1−x)₂O₃ barrier layer. Secondary ion mass spectroscopy and ECV measurements also revealed an unintentional Si peak at the (Al_xGa_1−x)₂O₃/Ga₂O₃ interface. Direct current (I_DS-V_GS) and transconductance (G_m-V_GS) measurements demonstrated depletion-mode transistor operation as well as the presence of a parallel conduction channel. A one-dimensional Poisson model suggested that dopant redistribution in the delta-doped region could cause a secondary channel to form in the barrier in addition to the primary channel near the (Al_xGa_1−x)₂O₃/Ga₂O₃ interface under certain conditions met in these samples. Fabricated devices on sample A did not exhibit breakdown up to the measurement limit of 1100 V, with stability after ten cycles. A maximum output drain current density of 22 mA/mm was measured on sample B. Room temperature Hall measurements yielded a sheet carrier density of 1.12 × 10¹³ cm⁻² with corresponding Hall mobility of 95 cm²/V s in sample C.

中文翻译：

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臭氧分子束外延掺杂δ-（AlxGa1-x）2O3 / Ga2O3异质结构场效应晶体管

首次展示了基于臭氧辅助分子束外延生长的β-（Al _x Ga _1-x）₂ O ₃ / Ga ₂ O ₃异质结构的异质结场效应晶体管。在本研究中生长的三个样品上，使用X射线衍射验证了14％–23％范围内的Al组成比。电化学电容-电压（ECV）测量表明，在δ掺杂（Al _x Ga _1-x）₂ O ₃势垒层中存在电荷片。二次离子质谱和ECV测量还发现在（Al _x Ga_1-x）₂ O ₃ / Ga ₂ O ₃接口。直流电（I _DS - V _GS）和跨导（G _m - V _GS）测量表明耗尽型晶体管工作以及存在并联传导通道。一维泊松模型表明，除了（Al _x Ga _1-x）₂ O ₃ / Ga ₂ O ₃附近的主要沟道之外，δ掺杂区中的掺杂物重新分布还可能导致在阻挡层中形成次要沟道。在这些样本中满足某些条件的界面。样品A上的预制器件在达到1100 V的测量极限之前都没有出现击穿现象，并且在十个循环后仍具有稳定性。在样品B上测得的最大输出漏极电流密度为22 mA / mm。室温霍尔测量得出的样品C中的薄层载流子密度为1.12×10 ¹³  cm ^-2，相应的霍尔迁移率为95 cm ² / V s。