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| 2. |
- GISLASON, HP, et al.
(författare)
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RADIATIVE RECOMBINATION IN N-TYPE AND P-TYPE GAAS COMPENSATED WITH LI
- 1993
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 74, s. 7275-7287
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Tidskriftsartikel (refereegranskat)abstract
- We report fundamental changes of the radiative recombination in a wide range of n-type and p-type GaAs after diffusion with the group-I element Li. These optical properties are found to be a bulk property and closely related to the electrical conductivity of the samples. In the Li-doped samples the radiative recombination is characterized by emissions with excitation-dependent peak positions which shift to lower energies with increasing degree of compensation and concentration of Li. These properties are shown to be in qualitative agreement with fluctuations of the electrostatic potential in strongly compensated systems. For Li-diffusion temperatures above 700-800-degrees-C semi-insulating conditions with electrical resistivity exceeding 10(7) OMEGA cm are obtained for all conducting starting materials. In this heavy Li-doping regime, the simple model of fluctuating potentials is shown to be inadequate for explaining the. experimental observations unless the number of charged impurities is reduced through complexing with Li. For samples doped with low concentrations of Li, on the other hand, the photoluminescence properties are found to be characteristic of impurity-related emissions.
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| 3. |
- GISLASON, HP, et al.
(författare)
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SHIFTING PHOTOLUMINESCENCE BANDS IN HIGH-RESISTIVITY LI-COMPENSATED GAAS
- 1993
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 47, s. 9418-9424
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that Li diffusion of GaAs can give rise to semi-insulating samples with electrical resistivity as high as 10(7) OMEGAcm in undoped, n-type, and p-type starting materials. The optical properties of the compensated samples are correlated with the depletion of free carriers caused by the Li diffusion. The radiative recombination of the Li-compensated samples is dominated by emissions with excitation-dependent peak positions that shift to lower energies with increasing compensation. The photoluminescence properties are characteristic of fluctuations of the electrostatic potential in strongly doped, compensated crystals.
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| 4. |
- HELMFRID, S, et al.
(författare)
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STIMULATED-EMISSION IN ER-TI-LINBO3 CHANNEL WAVE-GUIDES CLOSE TO 1.53-MU-M TRANSITION
- 1991
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 27, s. 913-914
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication and characterisation of Er:Ti:LiNbO3 channel waveguides is reported. A lifetime of 2.4 +/- 0.2 ms has been measured for the 4I13/2 level. In a pump and probe experiment using a high power InGaAsP laser and a tunable DBR laser, a signal increase of 0.75 dB for a transmitted pump power of 4.8 mW was demonstrated.
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| 5. |
- Linnarsson, Margareta K., et al.
(författare)
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Sputter profiling of AlGaAs/GaAs superlattice structures using oxygen and argon ions
- 1993
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 70-71:1, s. 40-43
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Tidskriftsartikel (refereegranskat)abstract
- Broadening of Al sputter profiles in AlxGa1-xAs/GaAs structures has been investigated using secondary ion mass spectrometry. The depth profiling was carried out with 32O+2 ions and 40Ar+ ions using net primary energies of 1.8, 2.2, 3.2 and 5.7 keV. The decay lengths of the Al profiles show a pronounced increase with increasing sputtering ion energy caused by ballistic mixing. Moreover, in the O+2 case the λ-values degrade with eroded depth, indicating that beam-induced surface roughening takes place during profiling and in particular, this holds for high x-values. The results are discussed in terms of a semi-empirical model for ion-beam-induced broadening developed by Zalm and Vriezema.
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| 6. |
- SVENSSON, BG, et al.
(författare)
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SIMS AND DEPTH PROFILING OF SEMICONDUCTOR STRUCTURES
- 1994
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 85, s. 363-369
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews recent secondary ion mass spectrometry (SIMS) work on (i) isotope shifts in ion implantation profiles, (ii) dopant profiles in silicon and beam-induced oxidation and (iii) surface roughness and profile broadening of Al(x)Ga1-(x)As/GaAs superlattice structures. Comparison is made with other techniques, and, in particular, the issues of depth resolution and conversion between sputtering time and sample depth are emphasized.
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