4-11 mu m infrared emission and 300 K light emitting diodes from arsenic-rich InAs_1-xSb_xstrained layer superlattices

Abstract

Arsenic-rich InAs/lnAsr-,Sbx strained layer superlattices (SLSs) grown on GaAs substrates by molecular beam epitaxy (MBE) are studied for their potential application as infrared emitters. The long-wavelength emission (4-1 1 pm) is highly sensitive to superlattice design parameters and is accounted for by a large type4 band offset, greater than in previously studied antimony-rich InSb/lnAs,_,Sb, SLSs. High internal PL efficiencies (>lo%) and intense luminescence emission were observed at these long wavelengths despite large dislocation densities. Initial unoptimized InAs/lnAsr_,Sb, SLS light emitting diodes gave ss200 nW of A = 5 pm emission at 300 K.In(AsSb) strained layer superlattices (SLSs) offer infrared detector and emitter applications beyond IO p m , Although mid-infrared lead salt lasers already exist they suffer from thermal conductivity, doping and metallurgical problems which have restricted their operation to temperatures below 200 K [l]. In(AsSb) offers superior metallurgical stability and compatibility with existing II-V technology compared to other infrared materials like cadmium mercury telluride. To date, because of the narrow bandgaps of the alloy constituents, InSb/InAsl-,Sb, SLSs composed of Sb-rich alloys have mainly been studied for long-wavelengh (510 pm) applications, notably longwavelength photodiodes [2]. The 10 pm response of the latter arises from the type-I1 band offset which gives a superlattice structure with an effective bandgap lower than either of the alloy constituents.The lack of lattice matched substrates, however, leads to defect densities of the order of (1-3) x IO9 cm-* (largely independent of alloy composition) in the active region of the device [3]. These give rise to Shockley-Read generation-recombination centres which limit the detectivity and emission efficiencies of Sb-rich alloy optoelectronic devices. In contrast, Walukiewicz [4] has shown that InAs is unique among the m-Vs in that pointlike lattice defects produce electronic states above the conduction band edge as opposed to in the forbidden gap.

Strain balanced InAs/InAsSb superlattice structures with optical emission to 10 μm

“…As the potential barrier for the charge carriers increases, the overlap of electrons in the InAsSb and holes in the InAs decreases and thus the PL signal decreases. Tang et al 14 also observed similar very long wavelength emission from InAs/InAsSb superlattice light emitting diode structures grown on GaAs substrates. The long emission wavelength was attributed to type IIa band alignment ͑electrons confined to InAsSb͒.…”

Energy gaps and lattice dynamic properties of InAsxSb1−x

“…This discrepancy is attributed to the neglect of the compositional disorder by the VCA method. Hence, a possible step beyond is to add to the VCA potential a non-periodic potential due to the compositional disorder as expressed in relation (2). By introducing the disorder effect potential to the VCA potential, the variation of E as a function of x is shown by the dotted curve in Fig.…”

“…This makes it an attractive material for a variety of mid-infrared optoelectronic devices, including lasers [2] and photo-detectors [3] and offers the possibility for replacing the HgCdTe materials most frequently used in the long-wavelength (8-12 m) and which are not easy to grow because of the difficulty in handling Hg [4]. Besides, InAs 1−x Sb x /InAs 1−y Sb y semiconductor alloys and hetero-junctions have been studied as potential infrared detectors and emitters [5].…”

Magnetotransport and Magnetooptics of InAs1-xSbxand Heterojunctions Combinations Formed Between InAs and GaSb, AlSb Or InAs1 -xSbx

“…The band offsets for the InΑs/ΙnΑs 1 -x Sbx superlattice system are the subject of some controversy with different groups variously putting forward type HA and type ΙIΒ alignments [1,2] on the basis of interband magnetoabsorption experiments performed at relatively low fields (< 10 T). In one case type I alignment coupled with strong narrowing of the band gap induced by Cu-Pt ordering in the alloy has also been proposed [3].…”