Failure mechanisms of AlGaAs/InGaAs pseudomorphic hemt's: Effects due to hot electrons and modulation of trapped charge

Factors Limiting the Maximum Operating Voltage of Microwave Devices

“…Creation of surface levels in the gatedrain access region is suggested by the increase in the downward dispersion of transconductance during the accelerated tests. 4 In InP-based HEMTs, InAlAs surface degradation with trap creation seems to be responsible for the damage leading to R D increase. In general, careful control of the characteristics of surfaces and interfaces seems to be crucial for good hardness against hot carrier degradation, the most critical region being the recessed gate area, where surface damage may also be induced by plasma treatments and/or wet etching.…”

Effects of deep levels on transconductance dispersion in AlGaAs/InGaAs pseudomorphic high electron mobility transistor

“…The transconductance of PHEMTs was decreased ͑negative transconductance dispersion͒ and/or increased ͑positive transconductance dispersion͒ with frequency. 4,5 The negative transconductance dispersion, commonly observed in GaAs metalsemiconductor field-effect transistors, was believed to be due to the surface states existing on the ungated regions between gate and source/drain electrodes. 1,6,7 The magnitude of the negative transconductance dispersion was dependent on the surface leakage current from the gate 1 and could be reduced after the surface passivation with Si 3 N 4 .…”

“…Several works have been independently conducted on the DX center using DLTS 9 and the transconductance dispersion measurements. 5 There was no work to show the direct relationship between the DX center and the transconductance dispersion. In PHEMTs with short gate periphery, the change of capacitance produced by the DX center was too small to be detected in capacitance transients.…”

Safe operating area of GaAs MESFET and PHEMT for amplification in overdrive operating conditions

“…It is generally believed that a direct correlation exists between the breakdown voltage stability and the reliability [1]. Indeed, when the devices are operating close to breakdown, the MESFETs and PHEMTs might present degradations due to hot electrons [2,3,4,5,6,7,8]. Worse yet, device reliability for new applications is not predictable until extensive life tests are performed [3].…”