Performance characteristics of In0.53Ga0.47As/In0.52Al0.48As modulation-doped field-effect transistors realized by two-step epitaxy: Effects of molecular-beam epitaxial regrowth

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Abstract
Epitaxial regrowth is emerging as an important step in the processing and realization of optoelectronic integrated circuits. We have studied the dc and microwave characteristics of regrown In0.53Ga0.47As/In0.52Al0.48As modulation‐doped field effect transistors on InP substrates and have compared these with the characteristics of normally grown devices. The low‐field transport properties of the heterostructures are degraded due to the increased interface roughness caused by processing and regrowth. The dc and microwave characteristics in terms of gm (399 mS/mm), fT (20 GHz), and fmax (35 GHz) are slightly degraded in the regrown devices compared to the normally grown ones. The density of states at the active heterointerface is not appreciably increased compared to normally grown devices. The low‐frequency 1/f noise level is higher in the saturation regime in the regrown devices. Our results indicate that there may be increased density of trapping centers in the regrown In0.52Al0.48As buffer layer below the active channel.