Room temperature operation of GaSb-based resonant tunneling diodes by prewell injection

Abstract

We present room temperature resonant tunneling of GaSb/AlAsSb double barrier resonant tunneling diodes with pseudomorphically grown prewell emitter structures comprising the ternary compound semiconductors GaInSb and GaAsSb. At room temperature, resonant tunneling is absent for diode structures without prewell emitters. The incorporation of Ga 0.84 In 0.16 Sb and GaAs 0.05 Sb 0.95 prewell emitters leads to room temperature resonant tunneling with peak-to-valley current ratios of 1.45 and 1.36 , respectively. The room temperature operation is attributed to the enhanced Γ -L-valley energy separation and consequently depopulation of L-valley states in the conduction band of the ternary compound emitter prewell with respect to bulk GaSb. a) Electronic mail to: Andreas. Pfenning@physik.uni-wuerzburg.de b) Electronic mail to: Fabian.Hartmann@physik.uni-wuerzburg.de The three semiconductors GaSb, InAs and AlSb of the so-called 6.1 Å family cover a wide range of bandgap energies and unique material properties, which make them particularly suitable for applications in high-speed electronics and as mid-infrared optoelectronic semiconductor devices. 1,2 During the past few years, application related research focused on mid-infrared light sources and detectors. 3,4 Especially the progress on interband cascade lasers (ICLs) and interband cascade detectors (ICDs) with type-II superlattice absorbers has driven the field. [5][6][7] In a recent publication we proposed an alternative mid-infrared photodetector concept based on resonant tunneling diodes (RTDs) with 6.1 Å family semiconductors. 8 RTDs can be exploited as highspeed and low-noise amplifiers of weak, optically excited electrical signals. 9-11 Unlike avalanche photodiodes, in which the multiplication gain originates from impact ionization, the RTD photodetection principle is based on the modulation of the resonant tunneling current via Coulomb interaction in presence of photogenerated minority charge carriers. [12][13][14] This mechanism provides very high amplification factors exceeding several hundred thousand at considerably low operation voltages. 10,11,15,16 The GaSb/InAs/AlSb material system has brought forth resonant tunneling structures (RTS) with unique and enhanced characteristics. prewell emitters leads to room temperature resonant tunneling with peak-to-valley current ratios of 1.45 and The HR-XRD spectrum of RTD 1 shows a single peak at Δ 0°, which indicates a good and high quality latticematched crystal growth of the RTD and the AlGaAsSb contact region. For RTD 2 and RTD 3, compressive and tensile strain secondary patterns arise at smaller and higher angles, respectively, caused by the incorporation of the pseudomorphically GaInSb and GaAsSb regions. The secondary pattern of RTD 2 is more pronounced compared to RTD 3 due to the three times higher In compared to As concentration.Circular RTD mesa structures with diameters from 2 µm up to 13 µm are defined by optical lithography and dry-chemical etching. The etching depth is about 50 nm below the dou...

GaSb/AlAsSb resonant tunneling diodes with GaAsSb emitter prewells

“…proposed to increase the In or As mole fractions of the prewell. 16 Here, we present a study on the electronic transport properties of AlAsSb/GaSb double barrier RTDs with pseudomorphically grown GaAsxSb1 x emitter prewell structures with increasing As mole fractions from % up to %. At room temperature, the resonance current density is found to increase with larger As mole fractions, which leads to enhanced peak to valley current ratios of ( %), ( %), and ( %).…”

“…A 10 nm wide GaSb capping layer with cm 3 completes the growth process. Further and more detailed information on the growth and fabrication process can be found in reference [16]. the nextnano software for simulation of electronic and optoelectronic semiconductor devices.…”

“…For a better comparison, the PVCRs for RTDs from Ref. [16] with GaAs0.05Sb0.95 (red square) and Ga0.84In0.16Sb prewell (blue diamond) are added to the graph. The PVCR of the RTD with GaAs0.05Sb0.95 emitter prewell is in good agreement with the extrapolation.…”

“…The PVCR is improved by a factor of four compared to RTD 1 and almost a factor of three compared to previously reported values. 16,15 Figure 4 (c) shows the PVCR of R 1 (black spheres), R 2 (red circles), RTD 1 (green up facing triangles) and RTD 3 (blue down facing triangles) as a function of temperature from K up to K. For all samples, the PVCR decreases with increasing temperature. At room temperature, the resonant tunneling structures containing the highest concentration of As show the largest PVCR, as caused by the successive population of the valley with electrons.…”

Innovative mid-infrared detector concepts

“…We are currently investigating different approaches on how to improve the electrical transport properties of GaSb-based resonant tunneling diodes at room temperature. [29] 4. CONCLUSIONS Two promising, novel and alternative detector concepts for the MIR region are demonstrated.…”