Abstract-We have carried out a systematic study of onstate breakdown in a sample set of InAlAs/InGaAs HEMT's using a new gate current extraction technique in conjunction with sidegate and temperature-dependent measurements. We find that as the device is turned on, the breakdown voltage limiting mechanism changes from a TFE-dominated process to a multiplication-dominated process. This physical understanding allows the creation of a phenomenological physical model for breakdown which agrees well with all our experimental results, and explains the relationship between BVon and the sheet carrier concentration. Our results suggest that depending on device design, either on-state or off-state breakdown can limit maximum power.Index Terms-Breakdown, HEMT, impact ionization, MOD-FET.

No abstract

This paper reviews recent progress in the development of GaAs metamorphic HEMT (MHEMT) technology for microwave applications. Commercialization has begun, while efforts to further improve performance, manufacturability and reliability continue. We also report the first multi-watt MHEMT MMIC power amplifiers, demonstrating up to 3.2W output power and record power-added efficiency (PAE) a t Ka-band.

Abstract-We have developed a methodology to diagnose the physical mechanisms limiting the manufacturing uniformity of millimeter-wave power InAlAs/InGaAs HEMT's on InP. A statistical analysis was carried out on dc figures of merit obtained from a large number of actual devices on an experimental wafer. correlation studies and principal component analysis of the results indicated that variations in Si delta-doping concentration introduced during molecular-beam epitaxy accounted for more than half of the manufacturing variance. Variations in the gate-source distance that is determined by the electron-beam alignment in the gate formation process were found to be the second leading source of manufacturing variance. The statistical methodology used in this work is suitable for continuous process yield diagnostics and improvement in a manufacturing environment.

We report the design, fabrication, and characterization of ultrahigh-gain metamorphic high-electron-mobility transistors (MHEMTs) with significantly enhanced breakdown performance. In this letter, an asymmetrically recessed 50-nm Γ-gate process has been successfully applied to epitaxial designs with double-sided-doped InAs-layer-inserted channels grown on GaAs substrates. The critical gate recess width has been optimized for device performance, including transconductance, breakdown voltage, and gain. The employment of a device passivation process greatly minimizes the adverse impacts that the aggressive vertical and lateral scaling would have introduced for pursuing enhanced performance. As a result, we have achieved 1.9-S/mm transconductance and 800-mA/mm maximum drain current at a drain bias of 1 V, 9-V off-state breakdown voltage, approximately 3.5-V on-state breakdown voltage, and 14.2-dB maximum stable gain at 110 GHz. To our knowledge, this is a record combination of gain and breakdown performance reported for microwave and millimeter-wave HEMTs, making these devices excellent candidates for ultrahigh-frequency power applications.Index Terms-Breakdown voltage, high-electron-mobility transistors (HEMTs), maximum stable gain (MSG), metamorphic HEMTs (MHEMTs), MODFETs, submillimeter-wave FETs.