Wavelength Uniformity Research Articles

Long wavelength GRIN-SCH MQW lasers incorporating graded GaAlInAs confinement layers

We report the growth and characterisation of the first GaAllnAs based GRIN-SCH MQW lasers operating at 1.3 and 1.6μm. In these devices, GaAllnAs barriers and either GalnAs or GaAllnAs wells have been used for the 1.6 and 1.3μm lasers, respectively, together with true continuously graded composition GaAlInAs regions for the confinement layers. The excellent structural quality of the active and confinement regions and control of wavelength uniformity has been confirmed. Buried ridge lasers fabricated from the GRIN-SCH MQW wafers lased at 1.3 and 1.6μm with CW threshold currents of 65 and 30 mA, respectively.

Large Area (100)CdTe and CdZnTe Layers on (100)GaAs Grown by Hot Wall Beam Epitaxy for Hgcdte Photovoltaic MWIR-Detectorarray Application

ABSTRACTThe newly developed Hot Wall Beam Epitaxy was used for the growth of (100)CdTe and (100)Cd1-yZnyTe layers (y ∼ 0.04) on 1 inch (100)GaAs wafers. The structural properties of the epilayers were investigated by means of high resblution x-ray rocking curve measurements. The results demonstrate the high crystalline perfection of the layers. The CdTe and Cd1-yZnyTe/GaAs wafers were used as substrates for the growth of Hg1-xCdx Te by close space vapor phase epitaxy. The layers show excellent homogeneity. Across a 1 inch wafer the composition x varies by ±0.0026, and the width of the rocking curve (FWHM) by ±10arcsec. Values of the FWHM as low as 50arcsec for Hg1-xCdxTe (x = 0.32) on Cd1-yZnyTe/GaAs were obtained. Linear arrays of planar photovoltaic detectors were fabricated. Arrays of 32 elements show high uniformity of the cutoff wavelength and the responsivity. The variation of the cutoff wavelength is ±1.5% (±0.04μm) and the variation of the responsivity is ±3%.

Raman spectra of AlxIn1−xAs grown molecular-beam epitaxy

Photoluminescence wavelength emission of GaxIn1−xAsyP1−y/InP heterostructures grown in multiwafer gas-source molecular-beam epitaxy (GSMBE) is studied in detail for both bulk and multiple quantum well (MQWs) heterostructures. Excellent photoluminescence wavelength uniformity is reported in 4×2-in. configuration, demonstrating the compatibility of GSMBE process with large-scale 1.55 μm telecom laser production. A strong dependence of wavelength uniformity on group-V/group-III flux ratio is reported and analyzed quantitatively. An empirical model based on the interplay between group-V elements incorporation and gas distribution is proposed to predict the influence of AsH3 and PH3 fluxes on As content in the solid. This understanding opens the way to an accurate tuning of wavelength dispersion of GaxIn1−xAsyP1−y/InP MQWs grown in multiwafer GSMBE system.

Structural properties of the ZnSe/GaAs system grown by molecular-beam epitaxy

Photoluminescence wavelength emission of GaxIn1−xAsyP1−y/InP heterostructures grown in multiwafer gas-source molecular-beam epitaxy (GSMBE) is studied in detail for both bulk and multiple quantum well (MQWs) heterostructures. Excellent photoluminescence wavelength uniformity is reported in 4×2-in. configuration, demonstrating the compatibility of GSMBE process with large-scale 1.55 μm telecom laser production. A strong dependence of wavelength uniformity on group-V/group-III flux ratio is reported and analyzed quantitatively. An empirical model based on the interplay between group-V elements incorporation and gas distribution is proposed to predict the influence of AsH3 and PH3 fluxes on As content in the solid. This understanding opens the way to an accurate tuning of wavelength dispersion of GaxIn1−xAsyP1−y/InP MQWs grown in multiwafer GSMBE system.

Wavelength uniformity of 1.3 μm GaInAsP/InP distributed Bragg reflector lasers with hybrid beam/vapour epitaxial growth

We report 1.3 μm distributed Bragg reflector (DBR) lasers with a hybrid growth employing base wafers grown by chemical beam epitaxy (CBE), and Fe-doped InP lateral current blocking grown by metal-organic chemical vapour deposition (MOCVD). These lasers display exceptional wavelength uniformity (σ ∼ 27 Å) across the wafer, and suggest that DBR lasers and vapour/beam growth techniques may be suitable for advanced WDM applications.

Growth of InGaAsP distributed feedback lasers by a modified single-phase LPE technique

The modified single phase technique has been used for the two-step LPE growth of distributed feedback type laser structures. Excellent surface morphology combined with highly reproducible layer thickness and composition has resulted in wafers which gave a high yield of lasers emitting in the 1.55 μm wavelength region. Furthermore, the wavelength uniformity of these lasers was of the order of tens of Angstroms.

Open tube vapor transport growth of Pb1−xSnxTe epitaxial films for infrared detectors

Epitaxial films of Pb1−xSnxTe have been grown by open tube vapor transport on (100) Pb1−xSnxTe substrates. The as-grown films are suitable for detector array fabrication with respect to both surface smoothness and electrical properties. Charge compositions from 1% excess metal to 1% excess Te were used. Growth rates up to 3–4 ym per hour were achieved. The asgrown carrier concentrations varied from 3 × 1016cm−3 to 3 × 1017cm−3 depending on growth temperature and charge composition. Schottky barrier detectors with semi-transparent electrodes were fabricated on as-grown layers with no surface preparation. Good uniformity of detector parameters was obtained with arrays of 20 to 40 elements. The array size is not limited by either substrate size or epitaxial quality. Resistance-area products on the order of 1 ohm-cm were obtained at 77 K for detectors with a 12 ym long wavelength cutoff. Quantum efficiencies for 8–12 urn radiation were 40–50%. Peak response and 50% cutoff occurred at 11 and 12 ym, respectively. Uniformity of cutoff wavelength across the arrays of ± 0.1 ym was obtained.