Design and Demonstration of (AlxGal-x)2O3/Ga2O3Double Heterostructure Field Effect Transistor (DHFET)

We report on the first demonstration of (AlxGal-x) 2 O 3 /Ga 2 O 3 double heterostructure field effect transistor using modulation doping. $\beta$ -phase Ga 2 O 3 has emerged as a promising candidate for a wide range of device applications, including power electronic devices, radio-frequency devices and solar-blind photodetectors. The wide bandgap energy and the predicted high breakdown field, together with the availability of low-cost native substrates, make $\beta$ -Ga 2 O 3 a promising material compared to other conventional wide bandgap materials, such as GaN and SiC. The use of bulk-doped $\beta$ -Ga203 channels makes it challenging to achieve device scaling. Recently, (AlxGal-x) 2 O 3 /Ga 2 O 3 modulation doped field effect transistor structures were demonstrated as a promising candidate for electronic device applications, showing the ability to improve channel mobility, and at the same time, achieve vertical scaling. High 2DEG charge density could potentially lead to better screening of the polar-optical phonon scattering at room temperature and therefore significantly enhance the electron mobility. However, the 2DEG density that can be confined in the modulation-doped structures without the introduction of parallel channels is limited by the conduction band offset at the hetero-interface and the spacer layer thickness. In this work, a modulation-doped double heterostructure field effect transistors (DHFET) is employed to further enhance the confined 2DEG density. Its electrical characterization will be discussed in this work.