Carrier reduction studies of type-II superlattice materials for very long wavelength infrared sensing

Abstract

There are continuing efforts to develop type-II superlattice (SL) materials for very long wavelength infrared (VLWIR) detector applications. However, the SLs have high residual electron background doping densities that depend on SL growth conditions, which lead to shorter minority carrier lifetime and lower performance parameters than theoretically predicted. In this study, the authors compare the technical advantages of using InAs/GaInSb over InAs/GaSb SL with respect to reducing the electron doping levels. Our temperature-dependent electrical transport measurements show that the InAs/GaInSb SL design has a lower electron density than the InAs/GaSb SL with the same bandgap and have electron densities (mobilities) on the order of the mid 1011 cm−2 (25 000 cm2/V s). Since small period InAs/GaInSb SLs also produce greater Auger recombination suppression for a given VLWIR gap than the large period InAs/GaSb SL, the InAs/GaInSb SL appears to be a better candidate for long lifetime IR materials for future very long wavelength infrared devices.

Long wavelength Infrared Detection, Bands Structure and effective mass in InAs/GaSb Nanostructure Superlattice

“…The semimetallic character and the semiconductor-semimetal transition of InAs/GaSb SL was studied experimentally well by transport and far infrared magneto-optical measurements by guldner et al [22]. We used the measured electron carrier density n as a function of the inverse of temperature by haugan et al [23], we determine the experimental band gap in the intrinsic domain by plotting nT -3/2 as a function of 1000/T. We found Eg= 95 meV, which is in agreement with 98 meV calculated at 300 K.…”

“…where kF 2D and kF 3D are the two dimensional and three dimensional Fermi wave vector respectively and n is the measured concentration of electron charge in the n(T) type sample [23]. The effective mass of electrons at the Fermi wave vector kF is m*E1(kF)=0.0284 m0.…”

“…We assist to an electronic conductivity transition Q2D-3D. Using the Hall mobility measured by [23] and our calculated effective mass of electrons m*E1, we calculated the transport scattering time p=H m*E1/e, we found 0.27 ps at 300 K. This value of p can be compared to the quantum relaxation time q= 0.5 ps and p=2.34 ps measured in AlGaN/GaN twodimensional electron gas [28]. We calculated also the velocity of electrons on the Fermi surface vF = ћkF/ m * EF, it is about 3.97 10 4 m/s.…”

Carrier recombination dynamics and temperature dependent optical properties of InAs–GaSb heterostructures

“…Furthermore, the photoluminescence (PL) properties of these structures are of interest to investigate the excitonic transitions and their correlation with the carrier recombination lifetime. The carrier lifetime of B80 ns was evaluated from the InAs/GaSb SLs by several researchers [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] by PL decay measurements and higher carrier lifetime is required for high performance photodetector. Haugan et al 36 demonstrated the long carrier lifetime of 140 AE 20 ns at B18 K for the InAs/ In 0.25 Ga 0.75 Sb SL structures compared to InAs/GaSb binary counterpart, and this enhancement was attributed to the strain-engineered ternary design and reduction of Ga-related Shockley-Read-Hall (SRH) recombination centers.…”

“…[42][43][44] These effects can introduce the interfacial disorder that can affect the carrier recombination properties of InAs/GaSb heterostructures. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] During the tailor-made, tunable-wavelength infrared PD and low-power tunnel transistor structure design, 46 a precise Ga, In, As and Sb flux sequencing technique is necessary during the growth to avoid interface intermixing and atomic segregation, reduced active region defect density, lowered interface roughness, and interfaces free from interfacial disorder, which all will improve the carrier lifetime in InAs/GaSb materials. If each interface of strain balanced GaSb/InAs/GaSb heterostructure (GaSb on InAs is 0.62% compressive strain and InAs on GaSb is 0.62% tensile strain) introduces interfacial disorders during growth, then the SL structure of many interfaces will magnify the interfacial disorder and hence will affect both the optical as well as carrier recombination properties.…”