M. de la Mare

Growth and characterization of InAsN/GaAs dilute nitride semiconductor alloys for the midinfrared spectral range

We report the growth of InAsN onto GaAs substrates using nitrogen plasma source molecular beam epitaxy. We describe the spectral properties of InAsN alloys with N-content in the range of 0%–1% and photoluminescence emission in the midinfrared spectral range. The photoluminescence emission of the sample containing 1% N reveals localized energy levels resonant with the conduction band states of InAsN.

Structural and optical properties of dilute InAsN grown by molecular beam epitaxy

We perform a structural and optical characterization of InAs1−xNx epilayers grown by molecular beam epitaxy on InAs substrates (x≲2.2%). High-resolution x-ray diffraction (HRXRD) is used to obtain information about the crystal quality and the strain state of the samples and to determine the N content of the films. The composition of two of the samples investigated is also obtained with time-of-flight secondary ion mass spectroscopy (ToF-SIMS) measurements. The combined analysis of the HRXRD and ToF-SIMS data suggests that the lattice parameter of InAsN might significantly deviate from Vegard’s law. Raman scattering and far-infrared reflectivity measurements have been carried out to investigate the incorporation of N into the InAsN alloy. N-related local vibrational modes are detected in the samples with higher N content. The origin of the observed features is discussed. We study the compositional dependence of the room-temperature band gap energy of the InAsN alloy. For this purpose, photoluminescence and...

Properties of dilute InAsN layers grown by liquid phase epitaxy

We report on the liquid phase epitaxial growth of InAsN from indium rich solution. The spectral properties of dilute bulk alloys containing N∼0.5% and which exhibit photoluminescence in the midinfrared spectral range without any postgrowth annealing are described. The blueshift in the emission spectrum is attributed to a combination of tensile strain and band filling effects.

Photoluminescence of InAs0.926Sb0.063N0.011/InAs multi-quantum wells in the mid-infrared spectral range

We report on the epitaxial growth and photoluminescence (PL) of InAs0.926Sb0.063N0.011/InAs multi-quantum wells (QWs) grown using plasma-assisted molecular beam epitaxy. These dilute nitride QWs exhibit bright PL in the mid-infrared spectral range up to a temperature of 250 K without any post-growth annealing. Consideration of the power dependent PL behaviour is consistent with a type I band line-up in these QWs, arising from a strong lowering of the conduction band edge due to N-induced band anti-crossing effects.

N incorporation and photoluminescence in In-rich InGaAsN grown on InAs by liquid phase epitaxy

Dilute nitride InGaAsN layers with high In content have been grown on InAs substrates by liquid phase epitaxy using GaN as a precursor for N in the growth solution. Photoluminescence (PL) was obtained in the mid-infrared spectral range at temperatures between 4 and 300 K. Although Ga increases the InAs bandgap, the strong band anti-crossing effect from the N incorporation resulted in an overall bandgap reduction of 11 meV compared with InAs. The temperature-dependent PL exhibited a complicated behaviour and showed an anomalous increase in intensity from 190 K to room temperature. This was due to the formation in a complex defect which behaves as a non-radiative recombination centre and prevents radiative band–band recombination at temperatures <190 K. Above this temperature the PL increases as band–band transitions become allowed. The formation of this defect requires the presence of both Ga and N and becomes de-activated after a high-temperature anneal. Raman spectroscopy confirmed the presence of phonon modes associated with In–N and Ga–N bonds confirming the incorporation of N using liquid phase growth.

Effects of substrate and N content on the growth of the mid-infrared dilute nitride InAsN alloy

We investigate the epitaxial growth of the dilute nitride InAsN alloy onto InAs and GaAs substrates with nitrogen content up to 1%. We report photoluminescence (PL) emission within the 2–4 µm spectral region and show that InAsN grown onto GaAs exhibits no degradation of the PL intensity and linewidth compared with epitaxial layers grown on near lattice-matched InAs substrates. Also, nitrogen can induce a significant reduction in the thermal quenching of the PL emission, which we attribute to the reduction in non-radiative Auger-recombination.

Room temperature mid-infrared InAsSbN multi-quantum well photodiodes grown by MBE

Room temperature photoresponse in the mid-infrared spectral region is demonstrated from InAsSbN/InAs multi-quantum well photodiodes grown by nitrogen plasma assisted molecular beam epitaxy. The structural quality of the InAsSbN MQWs was ascertained in situ by reflection high energy electron diffraction and ex situ by high resolution x-ray diffraction and photoluminescence measurements. The extended long wavelength photoresponse is identified to originate from the electron–heavy hole (e1–hh1) and electron–light hole (e1–lh1) transitions in the InAsSbN MQW, with a cut off wavelength ~4.20 µm and peak detectivity D *  =  1.25  ×  109 cm Hz1/2 W−1.

Midinfrared InAsSbN/InAs Multiquantum Well Light-Emitting Diodes

Electroluminescence is reported from dilute nitride InAsSbN/InAs multiquantum well light-emitting diodes grown using nitrogen plasma source molecular beam epitaxy. The diodes exhibited bright emission in the midinfrared peaking at 3.56 μm at room temperature. Emission occurred from a type I transition from electrons in the InAsSbN to confined heavy and light hole states in the QW. Analysis of the temperature- and current-dependent electroluminescence shows that thermally activated hole leakage and Auger recombination are the performance limiting factors in these devices.

InAs-based dilute nitride materials and devices for the mid-infrared spectral range

In this work we report on the characterization of InAsNSb dilute nitride alloys and mutli-quantum well structures. InAsN epilayers with room-temperature photoluminescence emission have been successfully grown by MBE on InAs and GaAs substrates. By careful attention to growth conditions, device quality material can be obtained for N contents up to ~3% with band gap reduction which follows the band anti-crossing model. Mid-infrared light-emitting diodes containing ten period InAsNSb/InAs multi-quantum wells within the active region were fabricated. These devices exhibited electroluminescence up to room temperature consistent with e-hh1 and e-lh1 transitions within type I quantum wells in good agreement with calculations. Comparison of the temperature dependence of the EL with that of type II InAsSb/InAs reveals more intense emission at low temperature and an improved temperature quenching up to T~200 K where thermally activated carrier leakage becomes important and further increase in the QW band offsets is needed. This material system shows promise for use in mid-infrared diode lasers and other optoelectronic devices.

MBE growth and characterization of dilute nitrides for mid-infrared optoelectronic devices

We report the molecular beam epitaxial growth of narrow gap dilute nitride InAsN alloys onto GaAs substrates using a nitrogen plasma source. The photoluminescence (PL) of InAsN alloys with N-content in the range 0 to 1% which exhibit emission in the mid-infrared spectral range is described. The sample containing 1% N reveals evidence of recombination from extended and localized states within the degenerate conduction band of InAsN. A comparison of GaAs and InAs based material shows little change in PL linewidth such that the change in substrate does not cause significant reduction in quality of the epilayers. The band gap dependence on N content in our material is consistent with predictions from the band anti-crossing model. We also report the growth of InAsSbN/InAs multi-quantum wells which exhibit bright PL up to a temperature of 250 K without any post growth annealing. Consideration of the power dependent PL behaviour is consistent with Type I band alignment arising from strong lowering of the conduction band edge due to N-induced band anti-crossing effects.