β‐(Al0.17Ga0.83)2O3/Ga2O3 Delta‐Doped Heterostructure MODFETs with an Ultrathin Spacer Layer and a Back‐Barrier Layer: A Comprehensive Technology Computer‐Aided Design Analysis

The output characteristics of β‐(Al 0.17 Ga 0.83 ) 2 O 3 /β‐Ga 2 O 3 ‐based heterostructure modulation‐doped field‐effect transistors (MODFETs) with an ultrathin spacer layer and a back‐barrier layer are fitted with experimental measurements using a Silvaco ATLAS technology computer‐aided design (TCAD) simulation environment, and the calibration of the physical model and material parameters is realized. The effects of spacer layer thickness, barrier layer thickness, Si‐δ doping density, and insertion of a β‐Ga 2 O 3 cap layer on the transfer and transconductance characteristics are examined. It is found that a β‐Ga 2 O 3 cap layer on the top of the heterostructure can increase the sheet carrier density in the heterostructure. A breakdown analysis is also carried out to reveal the effects of several layers on the off‐state characteristics. A range of channel layer thicknesses from 15 to 25 nm is found to be the optimum range to avoid a high off‐state leakage current and earlier breakdown voltage.