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We investigate the power switching mechanism to evaluate the power loss (PD) and efficiency (ɳ) in MgZnO/ZnO (MZO)‐based power heterostructure field effect transistor (HFET), and physical parameters responsible for PD in molecular beam epitaxy (MBE) and dual ion beam sputtering (DIBS) grown MZO HEFT and compare the performance with the group III‐nitride HFETs. This work extensively probes all physical parameters such as two‐dimensional electron gas (2DEG) density, mobility, switching frequency, and device dimension to study their impact on power switching in MZO HFET. Results suggest that the MBE and DIBS grown MZO HFET with the gate width (WG) of ~205 and ~280 mm at drain current coefficient (k) of 11 and 15, respectively, will achieve 99.96% and 99.95% of ɳ and 9.03 and 12.53 W of PD, respectively. Moreover, WG value for DIBS‐grown MZO HFET is observed to further reduce in the range of 112–168 mm by using a Y2O3 spacer layer leading to the maximum ɳ in the range of 99.98%–99.97% and the minimum PD in the range of 5–7 W. This work is significant for the development of cost‐effective HFETs for power switching applications.

This article analyzes the direct current and small-signal parameters of MgZnO/ZnO (MZO) HEMT for microwave application. Further, the impact of the MgO spacer layer on the microwave performance parameters such as transconductance (gm), cut-off frequency (fT), maximum oscillation frequency (fmax) and Johnson's figures of merit (J-FOM) of MZO HEMT has been analyzed. MZO HEMT with MgO spacer results in the enhanced values of two-dimensional electron gas (2DEG) density of 7.2×1013 cm-2 and gm of 91 mS/mm. The values of fT and fmax exhibit 3-fold enhancement to 5.57 GHz and to 7.8 GHz, respectively, and J-FOM is increased by 2.93 times with the introduction of MgO spacer layer in HEMT structure. Moreover, the impact of MgO spacer is studied on the off-state breakdown mechanism of MZO HEMT. The off-state breakdown voltage (Vbr) of MZO HEMT is ~25 V higher than that for MZO HEMT with an MgO layer. Therefore, there is a trade-off between the microwave performance and the device off-state breakdown voltage. This work is significant for the development of large-area and cost-effective ZnO-based HEMTs for microwave applications.

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