C.A. Beyler

GaAs/AlGaAs quantum well lasers with active regions grown by atomic layer epitaxy

Atomic layer epitaxy (ALE) is a relatively new crystal growth technique which allows control of the growth process at the monolayer level through a self‐limiting, surface‐controlled growth mechanism. We report here the use of ALE to grow high‐quality GaAs/AlGaAs quantum wells and the first successful demonstration of an injection laser with a quantum well active region grown by ALE. Room‐temperature threshold current densities as low as 640 A/cm2 have been achieved in nonoptimized separate confinement structures.

Atomic layer epitaxy for the growth of heterostructure devices

Abstract Atomic layer epitaxy (ALE) is a regime of metalorganic vapor phase epitaxial growth in which uniform growth of ultra-thin epitaxial layers by a self-limiting monolayer by monolayer deposition process is achieved. In this paper ALE has been applied to the growth of single crystal GaAs, AlAs and GaAs/AlGaAs heterostructures and devices. Data are presented that show one monolayer uniformity in ultra-thin layers grown by ALE. The dependence of growth rate on reactant flows and temperature are described. Cleaved corner TEM analysis of ALE epitaxial layer thicknesses demonstrates the “digital” nature of the deposition process. The low temperature photoluminescence (PL) of ALE grown GaAs quantum wells exhibit narrow line intrinsic luminescence with linewidths comparable to the best reported values by conventional MOCVD. Quantum well lasers with ALE grown active regions have been demonstrated with laser thresholds as low as 400 A/cm2.

Low-threshold quantum well lasers grown by metalorganic chemical vapor deposition on nonplanar substrates

Low-threshold quantum-well lasers having as-grown optical and electronic confinement fabricated by a single-step growth on nonplanar substrates are discussed. Several devices using various approaches for delineating narrow active regions by this technique are described. Fully planar index-guided arrays grown over a nonplanar substrate exhibit a threshold current of 8 mA per element. A technology called temperature engineered growth, which permits the formation of submicrometer active-region widths and wide contacting regions in the same growth step, is introduced. Lasers having active regions as narrow as 0.5 mu m grown using this technology display stable single-transverse-mode operation. CW threshold currents as low as 2.5 mA at room temperature with differential quantum efficiencies of 34%/facet were measured for uncoated devices. >

Temperature engineered growth of low-threshold quantum well lasers by metalorganic chemical vapor deposition

A new technique is demonstrated for the formation of narrow active regions in quantum well lasers. In temperature engineered growth (TEG), the substrate temperature is varied during the growth of epitaxial layers by metalorganic chemical vapor deposition (MOCVD) on nonplanar substrates, allowing two‐dimensional control of device features. Buried heterostructure designs with submicron active region stripe widths are obtained without the need for fine process control of lateral dimensions. The contact area above the active region is coplanar with the surrounding surface and wide enough to allow easy contacting and heat sinking. Carrier confinement is accomplished by lateral thickness variation of the quantum well active region resulting in a local strip of minimum band gap. Lasers grown in this manner exhibit cw threshold currents as low as 3.8 mA (3.4 mA pulsed), having an as‐grown active region width of 0.5 μm. The near‐field optical profile indicates stable, single transverse mode operation and minimal c...

Use of tertiarybutylarsine in the fabrication of GaAs/AlGaAs quantum wells and quantum well lasers

Tertiarybutylarsine was used in the growth of GaAs and AlGaAs by metalorganic chemical vapor deposition over a range of compositions and V/III ratios. GaAs layers were obtained with both n‐ and p‐type background carrier concentrations in the low 1014 cm−3 range. AlGaAs was grown at 20, 30, and 50% compositions, and photoluminescence of the Al0.2Ga0.8As indicates high quality material with full width half maximum (FWHM) values of the peaks being comparable to arsine‐grown AlGaAs. High quality multiple Al0.3Ga0.7As/GaAs quantum wells of various widths produced photoluminescence spectra with FWHM values comparable to arsine‐grown samples. Minority‐carrier lifetimes as long as 400 ns were measured for a heterostructure of 0.5 μm GaAs with Al0.3Ga0.7As barrier layers. Graded index separate confinement heterostructure lasers were fabricated, and broad‐ area test results of these devices produced threshold current densities as low as 186 A/cm2.

Low-threshold single-quantum-well InGaAs/GaAs lasers grown by metal-organic chemical vapor deposition on structure substrates

Low-threshold current (as low as 3.0 mA) and high-external efficiency ( approximately=88%) InGaAs/GaAs lasers emitting at 1 mu m under a stable fundamental transverse mode were obtained by using the temperature engineered growth technique for the growth on prepatterned substrates.<<ETX>>

Use of tertiarybutylarsine in atomic layer epitaxy and laser‐assisted atomic layer epitaxy of device quality GaAs

The use of trimethylgallium (TMGa) and tertiarybutylarsine (TBAs) in atomic layer epitaxy (ALE) and laser‐assisted atomic layer epitaxy (LALE) of GaAs is studied for the first time. TBAs is found to be a direct and suitable replacement for arsine (AsH3) in achieving monolayer self‐limiting growth. Carbon contamination in the GaAs films grown by LALE using TMGa and TBAs is greatly reduced relative to those using TMGa and AsH3. Laser structures single GaAs quantum wells grown by ALE and LALE using TBAs exhibit threshold current density as low as 300 and 520 A/cm2, respectively.

Characteristics of GaAs, AlGaAs, and InGaAs materials grown by metalorganic chemical vapor deposition using an on-demand hydride gas generator

We report results on the properties of GaAs, AlGaAs, and InGaAs materials grown using a new, on‐demand hydride gas generator. Low pressure arsine gas is generated from an arsenic containing precursor (KAsH2) by the controlled addition of water as a chemical activator. Both generated and bottled arsine are used to grow GaAs, AlGaAs, and InGaAs structures using atmospheric pressure metalorganic chemical vapor deposition. Using generated arsine, GaAs layers with background carrier concentrations of less than n=3×1013 cm−3 were produced across a growth temperature range of 625–725 °C using a V/III ratio of 30. InGaAs grown at 640 °C with V/III=30 exhibits a background carrier concentration of n=2.5×1014 cm−3 and mobility values of μ300 K=11 350 cm2/V s and μ77 K=71 200 cm2/V s. Photoluminescence measurements show highly resolved exciton spectra using either generated or bottled arsine with donor‐bound exciton linewidths as narrow as 0.16 meV full width at half‐maximum. Broad area GaAs/AlGaAs laser devices exh...

MOCVD Growth Of AlGaAs On Structured Substrates A New Tool For Device Design

Metalorganic Chemical Vapor Deposition (MOCVD) of AlGaAs and GaAs on structured substrates is investigated. Mesas and grooves formed by wet-etching are overgrown by alternating thin (< 50001) layers of AlGaAs and GaAs, allowing the observation of the time evolution of anisotropic growth near the etched features. Structures suitable for low-threshold lasers and low-loss waveguides are described and preliminary device performance is presented.