High Output Power Density of 2DHG Diamond MOSFETs With Thick ALD-Al2O3

• Published in: IEEE transactions on electron devices Vol. 68; no. 8; pp. 3942 - 3949
• Main Authors: Kudara, Ken, Imanishi, Shoichiro, Hiraiwa, Atsushi, Komatsuzaki, Yuji, Yamaguchi, Yutaro, Kawamura, Yoshifumi, Shinjo, Shintaro, Kawarada, Hiroshi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum oxide; Asymmetric structures; Atomic layer epitaxy; Diamond; Diamond field-effect transistor (FET); Electrodes; Field effect transistors; High voltages; Logic gates; metal-oxide semiconductor field-effect transistor (MOSFET); MOSFET; MOSFETs; output power density; Polycrystalline diamond; Power amplifiers; Power generation; Pull system; radio frequency; Self alignment; Semiconductor devices; Substrates; Two dimensional hole gas
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2021.3086457

This article reports on the high operation voltage large-signal performance of two-dimensional hole gas diamond metal-oxide semiconductor field-effect transistors (MOSFETs) with thick atomic-layer-deposition (ALD)-Al 2 O 3 formed on high purity polycrystalline diamond with a (110) preferential orientation. MOSFETs with a 1-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> gate-length having a gate oxide layer of 200-nm-thick Al 2 O 3 , formed by ALD and asymmetric structures, to withstand high-voltage operations. The large-signal performances were evaluated at a quiescent drain voltage of greater than −60 V for the first time in diamond field-effect transistor (FET). As a result, an output power density of 2.5 W/mm under class-A operation at 1 GHz, which is higher than that of diamond FETs fabricated by a self-aligned gate process, was obtained. Moreover, an output power density of 1.5 W/mm was exhibited by the MOSFET when biased at a quiescent drain voltage of −40 V under class-AB operation at 3.6 GHz using an active load-pull system. This is the highest recorded value for diamond FETs at a frequency greater than 2 GHz, owing to the high-voltage operation. These results indicate that diamond p-FETs under high-voltage operations are the most suitable for high-power amplifiers with complementary circuits.