M. P. Mikhailova

Interface-induced optical and transport phenomena in type II broken-gap single heterojunctions

This review deals with a study of optical and magnetotransport phenomena at a type II arsenide–antimonide heterojunction with a broken-gap alignment. A fundamental feature of this structure is partial overlapping of the InAs conduction band with the GaSb-rich solid solution valence band. In such a heterostructure, electrons and holes are spatially separated and localized in self-consistent quantum wells formed on both sides of the heterointerface. This leads to unusual tunnelling-assisted radiative recombination transitions and novel transport properties. Results of a pioneering study of interface-related luminescence in type II broken-gap GaInAsSb/InAs heterostructures, with a high quality abrupt heteroboundary, grown by the LPE method, are presented. The energy band diagram of the type II broken-gap GaInAsSb/InAs(GaSb) heterostructures and band overlapping control, depending on a doping level and epilayer composition of quaternary solid solution, are discussed. A 2D-electron channel with high Hall mobility at the p-GaInAsSb/p-InAs interface was found and examined. A great deal of attention is paid to quantum transport properties of the semimetal channel in a wide magnetic field range (up to 18 T) at low temperatures. A cyclotron resonance study was used to obtain data on the energy spectrum at the interface and to estimate effective masses for subbands in the semimetal channel. The intriguing behaviour of the 2D-electron system in the presence of localized holes in high magnetic fields and the first observation of integer quantum Hall effect plateaus on the type II single GaInAsSb/InAs heterointerface formed by LPE are demonstrated. A tunnelling-injection laser with high asymmetric band offset confinements based on the type II broken-gap heterojunction is considered. Applications of the interface-induced phenomena in luminescent and transport properties for the design of novel mid-IR optoelectronic devices and Hall sensors are briefly reviewed.

A 2.78-μm laser diode based on hybrid AlGaAsSb/InAs/CdMgSe double heterostructure grown by molecular-beam epitaxy

A mid-IR laser based on a hybrid pseudomorphic AlGaAsSb/InAs/CdMgSe heterostructure with a III–V/II–VI heterovalent interface at the 0.6-μm-InAs active region has been fabricated by molecular-beam epitaxy on p+-InAs substrate. It provides ∼1.5-eV asymmetric barriers for both electrons and holes in InAs, inhibiting carrier leakage from the active region. Despite a nonoptimal defect density at the CdMgSe/InAs interface (106–107 cm−2), the structure demonstrates lasing at ∼2.78 μm (up to 100 K) under pulse injection pumping with the threshold current density of 3–4 kA/cm2. The proposed design is promising for high-power mid-IR lasers operating at room temperature.

Optoelectronic sensors on GaSb- and InAs- based heterostructures for ecological monitoring and medical diagnostics

Light-emitting diodes (LEDs) and spectral-matched photodiodes (PDs) based on GaInAsSb/AlGaAsSb and InAs/InAsSbP heterostructures grown by LPE and MOVPE for the spectral range 1.6-4.8 μm are presented. New aproach have been proposed to increase quantum efficiency and optical power of the LEDs. Optical sensors based on the LEDs and PDs are considered for detection of methane, carbon dioxide and some anaesthetics for medicine.

Lasers And Avalanche Photodiodes For IR Fiber Optics In The 2-2,5 µm Spectral Range

In present work we report about development of semiconductor lasers and high-speed photodiodes based on GaInSbAs/GaAlSbAs solid solutions for 2.0-2.5 μm spectral range, which operate at the room temperature. Characteristics of.the lasers of several types are described. Among them there are pulsed lasers with output optical power reaching 1 W, cw lasers operating at room temperature at the wavelength of 2.0-2.2 μm, and pulsed lasers for the wavelength up to 2.5 μm. Properties of the developed photodetectors are also presented. There are described high-speed (τ<0.5ns) p-i-n photodiodes with quantum efficiency of 0.6 (without antire-flection coating) and avalanche photodiodes with separated absorbtion and multiplication regions (SAM APD), characterizing by multiplication factor of 20-30 at room temperature.

Superlinear electroluminescence due to impact ionization in GaSb-based heterostructures with deep Al(As)Sb/InAsSb/Al(As)Sb quantum wells

We report on the observation of superlinear electroluminescence (EL) in nanoheterostructures based on GaSb with a deep narrow Al(As)Sb/InAsSb/Al(As)Sb quantum well (QW) in the active region, grown by metal organic vapor phase epitaxy. Electroluminescence spectra for different driving currents were measured at temperatures of 77 and 300 K. It is shown that such structure exhibits superlinear dependence of optical power on the drive current and its increase of 2–3 times in the current range 50–200 mA. This occurs due to impact ionization in the Al(As)Sb/InAsSb quantum well in which a large band offset at the interface ΔEC = 1.27 eV exceeds ionization threshold energy for electrons in the narrow-gap well. Calculation of the size quantization energy levels is presented, and possible cases of impact ionization, depending on the band offset ΔEC at the interface and on the quantum well width, are considered. This effect can be used to increase quantum efficiency and optical power of light emitting devices (laser...

Staggered-lineup heterojunctions in the system of GaSbInAs

Abstract We present some results of investigations of the staggered-lineup (type II) heterojunctions between GaInSbAs solid solutions and GaSb. New bands have been observed in photoluminescence and electroluminescence spectra of the structures of different kind due to an existence of potential wells on both sides of a type II heteroboundary. An amplification of photocurrent has been found in the N-n structures, which we attribute to a modulation of transparency of a potential barrier for electrons at the heteroboundary by light induced holes captured in the potential well in the valence band. Features of the staggered-lineup heterojunctions were used for a development of some optoelectronic devices for a 1.5–2.5 μm spectral range.

Semiconductor lasers and photodiodes for gas analysis in the spectral range 1.8-2.5 μm

Semiconductor lasers and photodiodes for the 1.8-2.5 micron spectral range are described which can be used in gas analysis systems. The characteristics of pulsed lasers with output optical power reaching 1 W and low-threshold single-mode lasers are presented. The photodiodes have high quantum efficiency (0.6 without antireflection coating) and high speed or response (0.5 ns at reverse bias of several volts).

High-speed photodiodes for 2.0-4.0 μm spectral range

This paper reviews some recent developments in the high-speed photodiodes for 2.0-4.0 im spectral range. We report investigation, design and fabrication of broad bandwidth (2 GHz) GaInAsSb/GaA1AsSb p-i-n photodiodes operating in the 0.9-2.4 μm spectral range with submicroampere dark cunent. As well, we present InAs-based and InAs/InAsSbP photodiodes with long-wavelength cutoff of 3.8 μm. An analysis of the photodiode performance through the investigation of current-voltage, capacitance-voltage and spectral responsivity characteristics was carried out. Also, noise and speed-response characteristics were studied. In addition to high-speed response and low noise level these photodiodes offer room-temperature operation and hence are commercially viable. These devices are of great interest for a wide range of applications, such as high-resolution laser diode spectroscopy of gases and molecules, eye-safe laser rangefinding systems, the free-space optical link as well as systems of optical fiber communication.

Sensitivity of a receiver using GaInAsSb/AlGaAsSb SAM avalanche photodiode for long-wavelength optical communication systems in the mid-infrared spectral range

Low- noise avalanche photodiodes for the spectral range of 1.6-2.4 μm were created using the GaInAsSb solid solution in the absorption region and the wide-gap GaAlX(As)Sb alloy of resonant composition (x=0.04) in the multiplication region. This APD has a very high ratio of ionization coefficients, β/α>30 and low excess noise factor, F~1.6 (M=10). The sensitivity of a receiver for longwavelength communication (λ=1.6-2.5 μm) based on GaInAsSb/AlGa(As)Sb SAM APD is reported. The sensitivity for a direct detection receiver using the SAM APD was calculated according to the treatment of Personick at bit rate B=500 Mbit/s. The dependence of minimum detectable power η on multiplication M for the SAM APD for the wavelength λ=2.1 μm was calculated and compared with one for a standard Ge APD operating at λ=1.55 μm. A minimum detectable power level η = -42.3 dBm at Mopt=34-39 and η=-41.8 dBm at Mopt=10 of the receivers with the GaInAsSb/GaAl(As)Sb SAM APD and the Ge APD, respectively were obtained. These results demonstrate the potential of an optical receiver with the GaInAsSb/GaAl(As)Sb SAM APD for use in mid-IR wavelength optical communication system as well as of great interest for their potential applications in laser range-finding system.

Photovoltaic detector based on type II p-InAs/AlSb/InAsSb/AlSb/p-GaSb heterostructures with a single quantum well for mid-infrared spectral range

Mid-infrared photovoltaic detector (PD) designed on the base of a type II p-InAs/p-GaSb asymmetric heterostructure with a deep AlSb/InAsSb/AlSb quantum well (QW) at the interface is reported. The heterostructures containing the single QW were grown by LP-MOVPE. Transport, electroluminescent and photoelectrical properties of these structures were investigated. Intense both positive and negative electroluminescence was observed in the spectral range 3-4 µm above room temperature (300-400 K). Spectral response in the mid-infrared range 1.2-3.6 μm was obtained at temperatures T=77-300 K. High quantum efficiency η=0.6-0.7 responsivity Sλ=1.4-1.7 A/W and detectivity Dλ* =3.5×1011 cm Hz1/2w-1 were achieved at 77 K. Such QW PDs are suitable for heterodyne spectroscopy and free space communication using quantum cascade lasers as well as for gas analysis and ecological monitoring applications.