Effects of threading dislocations on drain current dispersion and slow transients in unpassivated AlGaN/GaN/Si heterostructure field-effect transistors

Saptarsi Ghosh, Syed Mukulika Dinara, Partha Mukhopadhyay, Sanjay K. Jana, Ankush Bag, Apurba Chakraborty, Edward Yi Chang, Sanjib Kabi, Dhrubes Biswas

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8 Scopus citations

Abstract

Current transient analysis combined with response to pulsed bias drives have been used to explore the possibilities of threading dislocations affecting the current dispersion characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs). A growth strategy is developed to modulate the dislocation density among the heterostructures grown on silicon by plasma-assisted molecular-beam epitaxy. Slow pulsed I-V measurements show severe compressions and appear to be significantly dependent on the threading dislocation density. By analyzing the corresponding slow detrapping process, a deep-level trap with emission time constant in the order of seconds was identified as the cause. Among the specimens, both in the epilayers and at the surface, the number of dislocations was found to have a notable influence on the spatial distribution of deep-level trap density. The observations confirm that the commonly observed degraded frequency performance among AlGaN/GaN HFETs in the form of DC-radio frequency dispersions can at least partly be correlated with threading dislocation density.

Original languageEnglish
Article number073502
JournalApplied Physics Letters
Volume105
Issue number7
DOIs
StatePublished - 18 Aug 2014

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