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

Abstract

The minority carrier lifetime (τ) of High electron mobility transistors (HEMTs) made using the InAlAs/InGaAs material system lattice‐matched to the InP substrate had been obtained from optical response measurements with a 1.55‐μm femto‐second pulse laser where the laser was illuminated onto the backside of a wafer. The drain current of HEMTs associated with the optical pulse was detected using a digitizing oscilloscope, and τ was estimated from the exponential dependence of drain current on time. In our current investigation, we found that τ is dominated by the following modes: (1) the amount of time required for holes to transit across the channel toward the source, and (2) the amount of time required for the holes accumulated in the source region to recombine with two‐dimensional electron gas (2DEG) through the Auger mechanism. Because the sheet concentration (ps) of holes accumulated in source region is low at a low source‐to‐drain voltage (VDS), Auger recombination is not predominant, and τ was only dominated by the hole transit time. At a high VDS, ps became high enough for Auger recombination to occur and dominate τ. Furthermore, we investigated the optical power dependence of τ where the optical power was supplied in a continuous wave (CW) to generate photo‐excited holes in a steady state. The value of τ decreased monotonically as VDS increased and saturated in as little as 6x10–10 s when the optical power was increased. The theoretical investigation was made to understand this saturation phenomenon. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Dc and Rf Characteristics Fluctuation of Inalas/Ingaas Hemts According to the Operating Temperature Variation

“…We have been studying the physical properties of a phenomenon expressed in high electron mobility transistors (HEMTs) of the kind used in ultra-highspeed field effect transistors (FETs) [3][4][5]. Our previous research on inhibitors of carrier transport led us to propose fusing a high-speed device with a photo-responsive device [6].…”

Characteristics of PHEMTs and MSM photodetectors simultaneously fabricated on same epitaxial wafer with In0.75Ga0.25As/InGaAs channel layer

“…A current-gain cut-off frequency (f t ) of 628 GHz [2] and a maximum oscillation frequency (f max ) of 1.2 THz have been reported [1]. In our previous study regarding the effect of optical irradiation on InAlAs/InGaAs HEMT characteristics, we demonstrated that a shift of threshold voltage (V TH ) in InAlAs/InGaAs HEMTs is caused by the change in the Fermi level due to the holes accumulated in the source region [3,4]. The carrier lifetime of accumulated holes is dominated by Auger recombination of holes in the two-dimensional electron gas (2DEG) [3][4][5].…”

“…Furthermore, we have shown that InAlAs/InGaAs HEMTs have a high responsivity when they are used as optical receivers [5]. Recently, we have demonstrated that InAs-PHEMTs can operate as not only high-speed transistors but as ultra-high speed optical receivers [3][4][5][6].…”

“…In our previous study regarding the effect of optical irradiation on InAlAs/InGaAs HEMT characteristics, we demonstrated that a shift of threshold voltage (V TH ) in InAlAs/InGaAs HEMTs is caused by the change in the Fermi level due to the holes accumulated in the source region [3,4]. The carrier lifetime of accumulated holes is dominated by Auger recombination of holes in the two-dimensional electron gas (2DEG) [3][4][5]. Furthermore, we have shown that InAlAs/InGaAs HEMTs have a high responsivity when they are used as optical receivers [5].…”

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].…”