Showing papers by "Nick Holonyak published in 1985"

Implantation disordering of AlxGa1−xAs superlattices

Abstract: Data are presented showing that layer disordering of Al x Ga1 − x As‐GaAs quantum wellheterostructures (QWH’s) or superlattices (SL’s) via ion implantation can be effected with a lattice constituent (Al), an inert ion (Kr), or an active impurity (Zn, Si, S, etc.). A doping impurity that diffuses (during annealing) via multiple sites, making column III sites available for Al‐Ga interchange, is most effective in layer disordering. However, any implanted ion is itself relatively effective in converting an Al x Ga1 − x As‐GaAs QWH or SL to bulk‐crystal Al y Ga1 − y As (0≤y≤x) via damage‐induced disordering.

Low threshold planar buried heterostructure lasers fabricated by impurity‐induced disordering

Abstract: We report on the fabrication of index‐guided buried heterostructure lasers by the process of silicon impurity‐induced disordering. This fabrication process for a buried heterostructure laser offers the advantage of reduced fabrication complexity over previous fabrication methods. We present measurements that demonstrate the operation of these devices in a single longitudinal mode, fundamental transverse mode, and with cw threshold currents as low as 3 mA. We also have extracted 80 mW cw from a device with a 10‐mA threshold current. Our results indicate that this process has great potential for the fabrication of low threshold, efficient light sources.

Low‐threshold disorder‐defined buried‐heterostructure AlxGa1−xAs‐GaAs quantum well lasers

Abstract: Two different quantum well heterostructure wafers are used to fabricate buried‐heterostructure AlxGa1−xAs‐GaAs quantum well lasers using Si‐induced layer disordering (via Si diffusion). In contrast to the first wafer (QWH1), the second quantum well wafer (QWH2) utilizes Zn instead of Mg as the p‐type dopant in the top AlxGa1−xAs confining layer and yields, because of concentration mismatch in acceptor and donor doping in the confining layers (nZn>nSe), inferior laser diodes owing to Zn diffusion from the p‐type to the n‐type confining layer during high temperature processing (850 °C Si diffusion). The first quantum well heterostructure, however, employs a lower concentration Mg doping for its p‐type confining layer (nMg

Stripe‐geometry AlxGa1−xAs‐GaAs quantum well heterostructure lasers defined by Si diffusion and disordering

Abstract: The use of Si diffusion and impurity‐induced layer disordering, via a Si3N4 mask pattern, to construct stripe‐geometry Al x Ga1−x As‐GaAs quantum wellheterostructure lasers on n‐type substrates is described. This leads to a convenient form of index‐guided buried‐heterostructure laser that is easily constructed and replicated (in various geometries) on commonly available n‐type GaAs substrate.

Impurity‐disordered, coupled‐stripe AlxGa1−xAs‐GaAs quantum well laser

Abstract: Continuous room‐temperature operation of impurity‐disordered, coupled‐stripe Al x Ga1−x As‐GaAs quantum wellheterostructure lasers is described. Silicon (donor) diffusion at 850 °C is used to produce layer disordering and index guiding, in addition to providing carrier confinement in a ten‐stripe coupled array (8‐μm‐wide stripes on 10‐μm centers).

Photoluminescence and stimulated emission in Si‐ and Ge‐disordered AlxGa1−xAs‐GaAs superlattices

Abstract: Photoluminescence and absorption data are presented on Al x Ga1−x As‐GaAs superlattices(SLs) disordered into bulk‐crystal Al y Ga1−y As (0≤y≤x) by Si or Gediffusion The bulk‐crystal Al y Ga1−y As produced by impurity‐induced disordering (by Al‐Ga interchange) is determined by transmission electron microscopy, absorption measurements, and photoluminescence to be homogeneous, with an alloy composition (y) that agrees with the average Al concentration of the SL For low enough Al concentration (y≊023

Transverse modes of gain‐guided coupled‐stripe lasers: External cavity control of the emitter spacing

Abstract: By means of an external grating cavity, the dispersion relation of the transverse modes of gain‐guided coupled‐stripe laser diodes is determined. The parabolic relation obtained indicates (despite the stripes) a relatively flat gain profile similar to a broad area laser. Accordingly, higher order transverse modes are possible and are demonstrated with near and far fields exhibiting one and two emitters per stripe.

Si‐implanted and disordered stripe‐geometry AlxGa1−xAs‐GaAs quantum well lasers

Abstract: The Si impurity is implanted into an Al x Ga1−x As‐GaAs quantum wellheterostructure to form, by impurity‐induced layer disordering and donor doping, a stripe‐geometry buried heterostructure laser.

Donor‐induced disorder‐defined buried‐heterostructure AlxGa1−xAs‐GaAs quantum‐well lasers

Abstract: A simple form of a buried heterostructure Al x Ga1−x As‐GaAs quantum‐well laser is described that is realized by impurity‐induced layer disordering (d o n o r‐i n d u c e d disordering). The layer disordering [and the resulting band‐gap shift to higher energy (and lower index)] is accomplished by Si diffusion in a stripe pattern defined by a Si3N4 mask. Single‐mode lasers of stripe width 3 and 6 μm are demonstrated that operate continuously at 300 K in the threshold current range of 10–25 mA and with single‐facet power levels as high as 10–20 mW.

Photoluminescence measurements of band discontinuity in InP‐InGaPAs heterostructures

Abstract: Photoluminescence data on liquid phase epitaxial single‐well quantum well heterostructures are presented that permit the determination of the valence‐band discontinuity ΔEv in InP‐In1−xGaxP1−yAsy heterostructures at several quaternary compositions matched to InP [x≊0.453y(1+0.031y)]. The ΔEv determination, which depends on a hot‐electron to bound‐hole recombination transition, indicates that ΔEv ≊0.35ΔEg and ΔEc ≊0.65ΔEg for all InGaAsP compositions lattice matched to InP.

Supermodes of multiple‐stripe quantum‐well heterostructure laser diodes operated (cw, 300 K) in an external‐grating cavity

Abstract: The far‐field supermode patterns of a phase‐locked multiple‐stripe quantum‐well heterostructure (QWH) laser diode are described as a function of injection current and emission wavelength, the latter controlled by an external grating. The external‐grating cavity is used to isolate single or multiple supermodes of the multiple‐stripe QWH laser (Pout>170 mW cw, λ∼7400 A). The progression of supermode patterns consists of a discrete set of mode configurations for each longitudinal mode of the spectrum. The progression is cyclic with a ∼2.8‐A period which corresponds to the longitudinal mode spacing of the diode. Under high gain conditions, i.e., near the center of the recombination‐radiation spectrum or at higher current levels, continuous tunability is observed with gradual transitions between supermode eigenstates. As the gain is reduced (low current), the number of supermodes observed decreases until only the in‐phase pattern, i.e., each emitter at the same phase, remains above threshold. The far‐field pat...

Hydrostatic pressure measurements (≲12 kbar) on single‐ and multiple‐stripe quantum‐well heterostructure laser diodes

Abstract: Short wavelength Alx’Ga1−x’As‐AlxGa1−xAs (x’∼0.85, x∼0.22) quantum‐well heterostructure (QWH) laser diodes (well size Lz ≊400 A) that operate continuously (cw) at 300 K are subjected to hydrostatic pressure (≲12 kbar). The emission spectrum and the light intensity versus current (L‐I) curves are monitored to determine the pressure dependence of the direct (Γ) band gap and the threshold current. The band gap exhibits a linear pressure dependence with a noticeable change in slope at ∼4.5 kbar, similar to previously reported results for AlxGa1−xAs‐GaAs QWH diodes. The threshold current increases monotonically with pressure, reflecting the increasing loss of carriers to the X and L bands. The short‐wavelength cw limit of the system, i.e., a gain‐guided laser with a 400‐A AlxGa1−xAs (x∼0.22) quantum well and no separate waveguide region, is determined to be ∼6980 A.

Broadband operation of coupled‐stripe multiple quantum well AlGaAs laser diodes

Abstract: A recently developed AlGaAs multiple stripe, multiple quantum well superluminescence light‐emitting diode (SLED) with an extremely low reflectivity front‐facet coating is operated as a high‐power laser in an external grating cavity over an unusually broad tuning range. The SLED diode is operated continuously (cw) in a tuning range Δℏω∼94 meV and a power output from the grating cavity of 75 mW (optical flux ∼500 mW within the compound cavity). Data are presented showing the output power as a function of wavelength at currents of 750 mA (7660 A<λ<8040 A) and 1.0 A (7620 A<λ<8085 A). The threshold current in pulsed laser operation is measured over a range of 130 meV.

Mode‐locked coupled‐stripe quantum well laser operation (λ∼7350 Å) in a tunable (Δℏω∼37 meV>kT) external grating cavity

Abstract: The performance of an actively mode‐locked coupled‐stripe Alx’Ga1−x’As‐AlxGa1−xAs quantum well laser in a tunable external cavity is described Pulses as short as 50 ps are measured and a tuning range of Δℏω∼37 meV>kT, which is not the limit, is demonstrated The existence of the transverse modes of coupled‐stripe lasers increases significantly the spectral density of available lasing modes (for mode locking) compared with a single‐stripe laser

Si‐Si pair diffusion and correlation in AlxGa1−xAs and GaAs

Abstract: The Si impurity is diffused into GaAs at temperatures in the range 725≤T≤850 °C. Secondary ion mass spectrometry(SIMS)analysis is used to obtain the Si atom density in the Si‐diffused layers. On the basis of the SIMS data and the observation of a distinct exciton peak in absorption for samples diffused at temperatures ≲775 °C, we argue that in the range n Si≲4×101 8/cm3 the Si impurity diffused into GaAs is correlated and is incorporated as Si‐Si nearest‐neighbor pairs.

Pressure dependence of AlxGa1−xAs light emitting diodes near the direct‐indirect transition

Abstract: High‐pressure studies on high quality AlxGa1−xAs double heterostructure light emitting diodes (LEDs) grown by liquid phase epitaxy (LPE) are presented The AlxGa1−xAs active region varies in composition from x∼025 to x∼053, ie, through the important region of the direct‐indirect crossover (x≡xc≊045) The pressure coefficient of the Γ conduction band is observed to decrease (∼1 meV/kbar for x∼025 to x∼053) with increasing Al concentration, which is in accord with alloy disorder and band‐edge bowing Indirect‐gap (X) recombination radiation of significant intensity is observed and provides evidence for the high quality of the LPE diodes High‐pressure measurements, and the corresponding increase in energy of the direct band edge and decrease in the indirect band edge, show that the light emission is a strong function of the carrier distribution in the Γ and X conduction‐band minima Comparison LEDs fabricated from a crystal (x∼037) grown by metalorganic chemical vapor deposition exhibit nearly simil