Double Heterostructure Lasers Research Articles

Dual gate material (Au and Pt) based double-gate MOSFET for high-speed devices

Aluminium Gallium Arsenide (AlGaAs) is a semiconductor material used in the latest design of double heterostructure laser diodes. This semiconductor is mostly available in the arbitrary alloy form between Gallium Arsenide and Aluminium Arsenide. It is derived from the Tri-MethylGallium (TMG/TMGa), and Arsine (AsH3), both the chemicals are pyrophoric and toxic. The resistance is less between source and drain contacts in the case of AlGaAs so that it has been proposed as a material to grow contacts on Indium Phosphide (InP) layer. The AlGaAs uses an ion implantation model for a design purpose which lowers the thermal power while the operation of the device. The parasitic capacitance has to be taken care of while designing a device using this material since the capacitance affects much in the AlGaAs based devices. The average velocity of the electrons has been observed to be increased by 14.63 % in the Au-gate (gate-1) and Pt-gate (gate-2) material-based Double-Gate (DG) MOSFET compared to the Silicon-based DG MOSFET. This paves the way for higher electron mobility, in turn, it can be used in highfrequency device manufacturing. The proposed material can be used in high-speed hybrid applications such as HEMTs and radiofrequency devices for long-haul communication.

Correlation of Defects and Lasing Threshold for AlGaN Deep Ultraviolet Lasers Grown by Molecular Beam Epitaxy

Herein, aluminum gallium nitride (AlGaN)/AlN double‐heterostructure (DH) laser at 287 nm with a lasing threshold of 530 kW cm−2 is shown. The laser structure is grown on the AlN‐on‐sapphire template by molecular beam epitaxy. This lasing threshold is drastically reduced compared with the previously reported AlGaN DH lasers at 297 nm with a threshold of around 1 MW cm−2. The detailed studies indicate that this improvement is mainly attributed to the control of defect formation largely due to the increased growth temperature of the AlGaN active layer. This is consistent with the improved internal quantum efficiency at low excitations. Moreover, the control of Al vacancy related point defects is clearly demonstrated by the absence of defect emission in the visible band.

Limitation of bulk GeSn alloy in the application of a high-performance laser due to the high threshold

In this work, the gain characteristics of the GeSn alloy are systematically investigated with effective mass approximation theory, and the potential of bulk GeSn in the application of a high-performance laser is discussed. The gain could not be enhanced persistently as the mole fraction of Sn continuously increases and becomes negative as the Sn fraction beyond 18%. An Sn fraction dependent doping scheme is proposed to effectively reduce the threshold injected carrier density to the lowest of 1.10×1018 cm-3. The optimum doping type varies from n-type to p-type as the Sn fraction increases with the conversion fraction of 10%. With doping optimization, the lowest threshold current density of bulk GeSn based laser is predicted to be 1.225 kA/cm2 for a designed n-Si0.157Ge0.643Sn0.200/p-Ge0.84Sn0.16/p-Si0.157Ge0.643Sn0.200 double heterostructure laser, indicating the inadequacy of bulk GeSn alloy of being the gain material for a high-performance laser.

Optimized High Performance Characteristics of a designed 450 nm InGaN/AlGaN True Blue Laser Considering Different Injection Current

In this work, the effects on the performance characteristics of a In0.1558Ga0.8442N / Al0.0416Ga0.9584N 3QW separate confinement heterostrcture 450 nm true blue edgeemitting laser are presented by considering different injection current. At the temperature of 300 K, the threshold current of the laser is 11 mA. The peak material gain for the designed laser is obtained as 1106 cm-1 and further used for the analysis of the performance characteristics of the designed doubleheterostructure laser for the variation of injection current. The injection current can be applied to the device is at around 12 to 15 times of the threshold current. At the value of injection current 152 mA, the maximum output power of the laser is 256.4 mW, the maximum resonance frequency is 14.5 GHz and the corresponding modulation bandwidth is 25.3 GHz at the temperature of 300 K.

Enhanced direct-gap light emission from Si-capped n+-Ge epitaxial layers on Si after post-growth rapid cyclic annealing: impact of non-radiative interface recombination toward Ge/Si double heterostructure lasers: erratum.

We report an error in Fig. 13(a) of our article [Opt. Express25, 21286 (2017)], and the correction is presented. Typographical errors in the text are also corrected.

Compact laser radar based on a subnanosecond laser diode transmitter and a two-dimensional CMOS single-photon receiver

A pulsed TOF laser radar utilizing the single-photon detection mode has been implemented, and its performance is characterized. The transmitter employs a QW double-heterostructure laser diode producing 0.6 nJ/100 ps laser pulses at a central wavelength of ∼810 nm. The detector is a single-chip IC manufactured in the standard 0.35-μm HV CMOS process, including a 9×9 single-photon avalanche diode (SPAD) array and a 10-channel time-to-digital converter (TDC) circuit. Both the SPAD array and the TDC circuit support a time gating feature allowing photon detection to occur only within a predefined time window. The SPAD array also supports a 3×3 SPADs subarray selection feature to respond to the laser spot wandering effect due to the paraxial optics and to reduce background radiation-induced detections. The characterization results demonstrate a distance measurement accuracy of +/−0.5 mm to a target at 34 m having 11% reflectivity. The signal detection rate is 28% at a laser pulsing rate of 100 kHz. The single-shot precision of the laser radar is ∼20 mm (FWHM). The deteriorating impact of high-level background radiation conditions on the SNR is demonstrated, as also is a scheme to improve this by means of detector time gating.

Enhanced direct-gap light emission from Si-capped n+-Ge epitaxial layers on Si after post-growth rapid cyclic annealing: impact of non-radiative interface recombination toward Ge/Si double heterostructure lasers.

Enhanced direct-gap light emission is reported for Si-capped n+-Ge layers on Si after post-growth rapid cyclic annealing (RCA), and impact of non-radiative recombination (NRR) at the Ge/Si interface is discussed toward Ge/Si double heterostructure (DH) lasers. P-doped n+-Ge layer (1 × 1019 cm-3, 400 nm) is grown on Si by ultra-high vacuum chemical vapor deposition, followed by a growth of Si capping layer (5 nm) to form a Si/Ge/Si DH structure. Post-growth RCA to eliminate defects in Ge is performed in N2 at temperatures between 900°C and 780°C, where the annealing time is minimized to be 5 s in each RCA cycle to prevent an out-diffusion of P dopants from the Ge surface. Direct-gap photoluminescence (PL) intensity at 1.6 µm increases with the RCA cycles up to 40, although the threading dislocation density in Ge is not reduced after 3 cycles in the present condition. The PL enhancement is ascribed to the suppression of NRR at the Ge/Si interface, where an intermixed SiGe alloy is formed. For Ge/Si DH lasers, NRR at the Ge/Si interface is found to have a significant impact on the threshold current density Jth. In order to achieve Jth on the order of 1 kA/cm2, similar to III-V lasers, the interface recombination velocity S is required below 103 cm/s in spite of S as large as 105 cm/s at the ordinary defect-rich Ge/Si interface.

(Electronics and Photonics Division Award Address) Compound Semiconductor Science and Technology: A Retrospective

From the earliest days, there has been interest in GaAs and other compound semiconductors due to higher electron mobility than silicon and suitability for optical applications. It was shown in 1962 that semiconductors such as silicon are not suitable for lasers and compound semiconductors were suggested. In the fall of 1962, several groups demonstrated semiconductor lasers under pulsed conditions at 77 K and double heterostructure (DH) laser diodes were achieved in 1970. Coinciding with major advances in fiber optics technology, this provided an enormous impetus for the development of compound semiconductor technology. Epitaxial crystal growth is a most important part of the technology. Liquid phase epitaxy was initially used but was replaced by vapor-phase and molecular beam epitaxy. MOCVD eventually became the vapor-phase technique of choice. Following a breakthrough in GaN technology in the 1990s, the impact of GaN technology is enormous and GaN-based LEDs are rapidly becoming the lighting technology of choice.

The concentration of energy from Edge Lasers by Diffractive Optical Component

The aim of this paper is to design a diffractive optical element based on the laser junction numerical model. We assumed a ?long? laser junction emitting quasi-monochromatic, spatially incoherent light that corresponds to the high power laser. Diffractive optics approach can be used due to the narrowband illumination. The especially designed numerical junction model was experimentally verified. Then a numerically designed diffractive focusing element was manufactured and tested in the experimental setup. This paper includes theoretical investigations, numerical modeling as well as experimental data. Full Text: PDF ReferencesE. Wolf, "New theory of partial coherence in the space?frequency domain. Part I: spectra and cross spectra of steady-state sources", J. Opt. Soc. Am. 72, 343 (1982). CrossRef E. Wolf, "Coherence theory of laser resonator modes", J. Opt. Soc. Am. A 1, 541 (1984). CrossRef A. Naqwi and F. Durst, "Focusing of diode laser beams: a simple mathematical model", Appl. Opt. 29, 1780 (1990) CrossRef J. Yang, T. Chen, G. Ding and X. Yuan, "Focusing of diode laser beams: a partially coherent Lorentz model", Proc. SPIE 6824, 68240A (2007); CrossRef X. Zeng and A. Naqwi, "Far-field distribution of double-heterostructure diode laser beams", Appl. Opt. 32, 4491 (1993). CrossRef Y. Li and J. Katz, "Nonparaxial analysis of the far-field radiation patterns of double-heterostructure lasers", Appl. Opt. 35, 1442 (1996). CrossRef X. Zeng, Z. Feng, and Y. An, "Far-field expression of a high-power laser diode", Appl. Opt. 43, 5168 (2004) CrossRef J. Tervo, J. Turunen, P. Vahimaa, and F. Wyrowski, "Shifted-elementary-mode representation for partially coherent vectorial fields", J. Opt. Soc. Am. A 27, 2004 (2010). CrossRef J. Turunen, "Elementary-field representations in partially coherent optics", J. Mod. Opt. 58, 509 (2011). CrossRef H. Partanen, J. Tervo, and J. Turunen, "Spatial coherence of broad-area laser diodes", Appl. Opt. 52, 3221 (2013) CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Commun., 116, 43 (1995) CrossRef Z. Jaroszewicz, A. Kolodziejczyk, M. Sypek, C. Gomez-Reino, "Non-paraxial analytical solution for the generation of focal curves", J. Mod. Opt., 43, 617 (1996) CrossRef M. Sypek, C. Prokopowicz, M. Gorecki, "Image multiplying and high-frequency oscillations effects in the Fresnel region light propagation simulation", Opt. Eng., 42, 3158 (2003) CrossRef C. Prokopowicz, "Numerical calculation of light propagation in off-axis region", Proc. SPIE, 5484, 482 (2004). CrossRef A. Sobczyk, Z. Jaroszewicz, A. Kolodziejczyk, A. Kowalik, Cz. Prokopowicz, M. Sypek, "Nonparaxial anamorphic diffractive lenses", J. Opt., 15, 025702 (1-5) (2013) CrossRef

About the physical meaning of the critical temperature for catastrophic optical damage in high power quantum well laser diodes

It is usually assumed that the catastrophic optical damage of high power laser diodes is launched when a critical local temperature (Tc) is reached; temperatures ranging from 120 °C to 200 °C were experimentally reported. However, the physical meaning of Tc in the degradation process is still unclear. In this work we show that, in the presence of a local heat source in the active region, the temperature of the laser structure, calculated using finite element methods, is widely inhomogeneously distributed among the different layers forming the device. This is due to the impact that the low dimensionality and the thermal boundary resistances have on the thermal transport across the laser structure. When these key factors are explicitly considered, the quantum well (QW) temperature can be several hundred degrees higher than the temperature of the guides and cladding layers. Due to the size of the experimental probes, the measured critical temperature is a weighted average over the QW, guides, and claddings. We show the existence of a large difference between the calculated average temperature, equivalent to the experimentally measured temperature, and the peak temperature localized in the QW. A parallel study on double heterostructure lasers is also included for comparison.

Diffusion-drift model of the transport of charge carriers and photons in injection lasers

A mathematical model is proposed that can be used for numerical analysis of the dynamics of processes in injection lasers with allowance for their structural features; nonuniform spatial distributions of electrons, holes, and photons; and various mechanisms of radiative recombination. Results of numerical modeling of double-heterostructure injection lasers performed using the proposed model are compared to the results obtained using the equations of laser kinetics. Boundaries of applicability of these models are considered.

ATLAS simulation of a laser diode for free space optical communication (FSOC) in mid-infrared spectral region

AbstractIn this paper, simulation studies on an N+-InAs0.61Sb0.13P0.26/n0-InAs0.97Sb0.03/P+-InAs0.61Sb0.13P0.26 double heterostructure laser diode suitable for use as a source in a free space optical communication system at 3.7 μm at room temperature has been presented. The device structure has been characterized in terms of energy band diagram, electric field profile, and carrier concentration profile using ATLAS simulation tool from Silvaco. The current-voltage characteristics of the structure have been estimated taking into account the degeneracy effect. The results of simulation have been validated by the reported experimental results.

Heterostructures for Optoelectronics: History and Modern Trends

Semiconductor revolution of the 20th century determined not only technological, but also social development of the modern society. The precursors of modern semiconductor electronics were Oleg Losev's discoveries of “crystadine” and “light-emitting diode (LED)” nearly 100 years ago. Creation of the transistor and semiconductor laser and LED based on the homo p-n structure became the most decisive step. Semiconductor optoelectronics was born with the creation of GaAs and GaAsP lasers and “LED.” The possibility to control the type and level of conductivity and injection in p-n junctions was the seed from which semiconductor electronics developed. Heterostructures-“man-made crystals”-solved a more general problem: the necessity to control electron and photon fluxes in crystals. The development of physics and technology for semiconductor heterostructures resulted in drastic changes in our everyday life. It is hardly possible to imagine our recent life without double-heterostructure (DH) laser-based telecommunication systems, without efficient DH LEDs, heterostructure bipolar transistors, and high electron mobility transistors (HEMTs) for high-frequency applications. DH lasers were introduced in every household with CD players. Heterostructure solar cells have been widely used for space and terrestrial applications. The first proposals for heterostructures in semiconductor devices were made as early as in the 1950s, but the most important experimental results were received at the end of the 1960s when the first ideal AlGaAs heterostructures and low threshold room-temperature lasers, efficient heterostructure LEDs, and solar cells were created. Later semiconductor heterostructure became laboratories of low-dimension electron gases. Molecular-beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) technologies were the basis for the development of new structures, including superlattices, and for the industrial production of a large family of heterostructure semiconductor devices. Quantum dot (QD)-based optoelectronics as a modern trend in optoelectronics is the subject of a more detailed consideration.

The Double-Heterostructure Concept: How It Got Started

The double-heterostructure (DH) concept for lasers and light-emitting diodes (LEDs) grew out of the prelaser context of increasing the speed of the early bipolar junction transistors. The 1954 idea was to change the energy gap itself, with a graded-gap base, or a wide-gap emitter. This led to the 1957 more general concept of quasi-electric fields and potentials in structures with a position-dependent energy gap. This paper gives a personal chronological account of the evolution of these concepts toward the 1963 proposal of the DH laser, including some blind alleys and blunders along the way.

Absorption cross-sections of hole polarons in glassy and β-phase polyfluorene

Absorption induced by electrochemically injected holes is studied in poly-9,9-dioctylfluorene (PFO) films. Injected charges form positive polarons which are delocalised over four fluorene units in the glassy phase and about seven fluorene units in its β-phase. Polaron absorption cross-sections at the 640nm peak are similar to the published values of chemically reduced oligofluorenes in solution. The absorption cross-section of polaron in the β-phase at 470nm is about eight times smaller than the stimulated emission cross-section derived from published data. This indicates that β-phase-rich PFO is an attractive candidate for a light-emitting layer in double-heterostructure organic laser diodes.

Theoretical Analysis of GeSn Alloys as a Gain Medium for a Si-Compatible Laser

In this paper, a theoretical analysis of unstrained GeSn alloys as a laser gain medium was performed. Using the empirical pseudopotential method, the band structure of GeSn alloys was simulated and verified against experimental data. This model shows that GeSn becomes direct bandgap with 6.55% Sn concentration. The optical gain of GeSn alloys with 0-10% Sn concentration was calculated with different n-type doping concentrations and injection levels. It is shown theoretically that adding Sn greatly increases the differential gain owing to the reduction of energy between the direct and indirect conduction bands. For a double-heterostructure laser, the model shows that at a cavity loss of 50 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the minimum threshold current density drops 60 times from Ge to Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.9</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</sub> , and the corresponding optimum n-doping concentration of the active layer drops by almost two orders of magnitude. These results indicate that GeSn alloys are good candidates for a Si-compatible laser.

13 μm InAs/GaAs quantum dot lasers on Si rib structures with current injection across direct-bonded GaAs/Si heterointerfaces

An InAs/GaAs quantum dot laser on a Si rib structure has been demonstrated. The double heterostructure laser structure grown on a GaAs substrate is layer-transferred onto a patterned Si substrate by GaAs/Si direct wafer bonding without oxide or metal mediation. This Fabry-Perot laser operates with current injection through the GaAs/Si rib interface and exhibits InAs quantum dot ground state lasing at 1.28 μm at room temperature, with a threshold current density of 480 A cm(-2).

Special Issue Dedication: James J. Coleman

This special issue of IEEE Journal of Quantum Electronics on Optoelectronic Device Integration is dedicated to Professor James J. Coleman on the occasion of his 60th Birthday. Dr. J.J. Coleman (S'73-M'76-SM'80-F'92) received the B.S., M.S., and Ph.D. degrees in electrical engineering from the University of Illinois at Urbana-Champaign, Urbana. He studied MOCVD-grown heteroface AlGaAs solar cells, lowthreshold single mode AlGaAs-GaAs double heterostructure lasers, and quantum well heterostructure laser devices at Rockwell International, Anaheim, CA. A brief review of Dr. Coleman's professional contributions is presented.

Epitaxial Structure Design of a Long-Wavelength InAlGaAs/InP Transistor Laser

The threshold condition in long-wavelength InAlGaAs/InP transistor lasers is theoretically and numerically investigated. The optical gain in the In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.58</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.42</sub> As/In(Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> )As strained quantum well is calculated using a simplified <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> -selection model while intervalence band absorption is considered as the major intrinsic optical loss in the transistor lasers. It is found that room-temperature lasing of an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -InP/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> -In(Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> )As/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -InP double heterostructure transistor laser is achieved only when the base thickness and doping level are within a specific narrow range. However, the selectable range is significantly expanded by means of facet coating, structure engineering, and quantum well design. By using a more compressively-strained or thicker quantum well as the active region in a separate confinement heterostructure transistor laser, it is possible to obtain a threshold current density as low as sub-100 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Development history of the laser

An attempt is made at objectively assessing the contribution made by Soviet scientists to the origination of laser physics, which the author believes tends to be underestimated abroad. Together with the concept of induced radiation, the three-level method and the open resonator were to become cornerstone proposals for laser physics, as were semiconductor active media, carrier injection through the p–n junction, double heterostructure lasers, and laser fusion.