Frequency Dependence of Drain Conductance due to Hole Accumulation in InAlAs/InGaAs High Electron Mobility Transistors

Abstract

The frequency dependencies of the drain conductance (G d ) and the responsivity of InAlAs/InGaAs high electron mobility transistors were investigated using a network analyzer. The G d exhibited the same frequency dependence as responsivity under 1.3-mm-wavelength laser illumination, indicating that the frequency dependence of G d arises from the recombination of holes that have accumulated in the source region with the two-dimensional electron gas (2DEG). The holes were generated in the drain region by impact ionization under the strong electric field and drifted toward the source region. The drain conductance due to impact ionization can be expressed as Lorentz frequency dependence with f 3dB being the 3-dB-down frequency. The minority carrier (hole) lifetime, , was estimated using the relation 1=2 f 3dB . The frequency dependence of G d at several drain-to-source and gate-to-source voltages was investigated. The recombination lifetime for a system in which both electrons and holes co-exist was theoretically estimated, taking account of self-consistent solutions of both the Schrödinger and Poisson equations and the nonradiative Auger recombination mechanism. The experimental and theoretically estimated results clearly show that the frequency dependence of G d is caused by the accumulation of holes in the source region and their recombination with the 2DEG. Based on the experimental and theoretical results, the distribution of holes in the channel and the multiplication factor due to the impact ionization are discussed in details.

Dependence of Carrier Lifetime of InAlAs/InGaAs High-Electron-Mobility Transistors on Gate-to-Source Voltage

“…Here, was obtained according to the method described in ref. 12, in which f 3dB is obtained from the experimental data for the frequency dependence of G d and then is calculated using the relation f 3dB ¼ 1=2. For convenience, the effective drain-gate voltage V DG,eff applied to the side of the gate-to-drain path is defined as V DS -V DS,sat following a method reported elsewhere, 2) where V DS,sat is the drain-to-source voltage defined in such a way that d 2 I DS =dV DS 2 is at a minimum.…”

“…This result is consistent with that shown in the previous paper. 12) Next, the result for the V GS dependence of will be discussed qualitatively. The concentration of holes generated by impact ionization in the drain region increases with V GS because the concentration of 2DEG injected into the drain region increases with V GS .…”

InAlAs/InAs/InGaAs pseudomorphic high electron mobility transistors exhibiting ultra‐fast optical response

“…The carrier lifetime of accumulated holes is dominated by the recombination of holes with two-dimensional electron gas (2DEG) [5,6]. Furthermore, we showed that InAlAs/ InGaAs HEMTs have a high responsivity when they are used as optical receivers [7].…”

Analysis of minority carrier lifetime for InAlAs/InGaAs high electron mobility transistors by using 1.55‐μm femto‐second pulse laser

“…In addition, the carrier lifetime of accumulated holes is dominated by the recombination of holes with twodimensional electron gas (2DEG) [5,6]. We previously demonstrated that the frequency dependence of drain con-ductance (G d ) is caused by the accumulation of holes in the source region and their recombination with 2DEG.…”

“…In addition, it was demonstrated that the non-radiative Auger recombination is the dominant mechanism when holes recombine with 2DEG. Furthermore, the minority carrier lifetime due to Auger recombination has been estimated using G d with the effective drain-gate voltage (V DG.eff ) increased [5,6].…”