IVA-2 impact ionization coefficients for electrons and holes in alloys of GaAs1-xSbx (original) (raw)
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Impact ionization rates for electrons and holes in GaAs1−xSbx alloys
Applied Physics Letters, 1976
In this paper preliminary experimental results are shown on Hg0 3Cd07Te avalanche photodiodes with x = 0.70 and E5 = 0.84 eV. In the first part, both multiplication coefficients M5 and M~0are determined. The ionization coefficients a and /3 for electrons and holes are calculated. The ionization coefficient ratio, k = /3/a, is deduced and is about 10. In the second part, noise characterization will be presented. The excess noise F(M), given by McIntyre's theory, confirms that k is about 10.
Photonics Letters of Poland
Dark resistivity and electrooptic effect are two of the necessary conditions crucial for the photorefractive effect to occur. Proton implantation used for increasing the dark resistivity of semiconductor heterostructures can influence the electrooptic coefficient. In this paper, there are presented the results of absorption and electroabsorption spectra measurements in semi-insulating GaAs/Al0.3Ga0.7As multiple quantum well (MQW) structures. The dependence was analyzed between the electroabsorption amplitude near the excitonic peaks and the different proton implantation parameters.
Investigation of impact ionization in thin GaAs diodes
IEEE Transactions on Electron Devices, 1996
The electron and hole multiplication coefficients, Me and lwh, respectively, have been measured in thin GaAs homojunction PIN and NIP diodes and from conventional ionization analysis the effective electron and hole ionization coefficients, a and /?, respectively, have been determined. The nominal intrinsic region thickness (U of these structures ranges from 1.0 bcm down to 25 nm. In the thicker structures, bulk-like behavior is observed; however, in the thinner structures, significant differences are found. As the i-regions become thinner and the electric fields increase, the M c / M h ratio is seen to approach unity. The experimental results are modeled and interpreted using a semianalytical solution of the Boltzmann equation. In thin (w < 0.1 pm) devices the dead space effect reduces effective ionization coefficients below their bulk values at low values of carrier multiplication. However, overshoot effects compensate for this at extremely high fields (21 x lo3 kV/cm).
Electroabsorption modulators operating at 1.3 ?m on GaAs substrates
Optical and Quantum Electronics, 1993
This paper describes the growth and device performance of electroabsorption modulators on GaAs substrates operating near 1.3#m, the dispersion minimum for silica fibres. The key to the successful molecular beam epitaxial (MBE) growth of these devices was the incorporation of a linearly-graded buffer layer beneath the InGaAs/ AIGaAs multi-quantum-well active layer. Both transmission and reflection modulators are produced. For transmission devices, larger modulation is achieved when the buffer is graded more slowly. The maximum modulation reported was 22% for AT/To corresponding to a 0.86dB contrast ratio with an insertion loss of roughly 5dB at 1.34#m. Antireflection coating a transmission modulator yields a reasonable reflection modulator. However, improved performance is reported for a reflection modulator using a novel technique of integrating the bottom quarter-wave mirror into a buffer with linearly-graded In composition. At 1.33 #m, a normally-off reflection modulator with an integrated mirror exhibited a AR/R o of 73%, a contrast ratio of 2.38 dB, and an insertion loss of 4dB.
Defect identification in electron-irradiated GaAs
Physical Review B, 1982
The introduction rates of the main electron traps created by electron irradiations have been measured as a function of the composition of the Ga& "Al"As solid solution system in the 0 (x (0.5 range; they are not x dependent. Discussing the recent results given in the literature, it appears that the defects created could be Vzs and Izs.
Impact ionization in Al x Ga 1؊x As/GaAs superlattices
The role of band discontinuities on electron ionization rates is examined for the case of GaAs/ AlGaAs superlattice avalanche photodiode structures. Our results show that the energy discontinuity experienced by a hot electron (EϾ0.4 eV above the Fermi level͒ is small or even negative relative to the conduction-band energy discontinuity experienced by an electron at the band edge of the ⌫ valley in GaAs/AlGaAs heterostructures. This finding does not support the measurement of an enhanced electron ionization rate due to transport through a superlattice composed of this materials system.
Journal of Applied Physics, 1994
The performance of Schottky contact semiconductor radiation detectors fabricated from semi-insulating GaAs is highly sensitive to charged impurities and defects in the material. The observed behavior of semi-insulating GaAs Schottky barrier alpha particle detectors does not match well with models that treat the semi-insulating material as either perfectly intrinsic or as material with deep donors (EL2) of constant capture cross section compensated with shallow acceptors. We propose an explanation for the discrepancy based on enhanced capture of electrons by EL2 centers at high electric fields and the resulting formation of a quasineutral region in the GaAs. Presented is a simple model including field enhanced electron capture which shows good agreement with experimental alpha particle pulse height measurements. 7910
Electroabsorption properties of a single GaAs quantum well
Physical Review B, 1991
Data are presented on the electroabsorption spectra of a single 10-nm GaAs quantum well bounded within Alo zGao 8As under conditions for which the excitonic features are unresolved. Over an electricfield range of 100-500 kV/cm, the spectra are bounded by twoand three-dimensional electroabsorption limits. The three-dimensional limit occurs because of strong tunnel coupling to the continuum states, resulting in lifetime broadening of the transitions. Model studies using the one-electron-overlap-integral picture confirm this behavior and predict absorption coef5cients and spectra in reasonable agreement with the data. Estimates of the high-field lifetime suggest that use of this mechanism for a practical modulator would reduce some of the intensity and recovery-time limitations of traditional exciton-based modulators.
SI-GaAs detectors with epitaxial junction
IEEE Transactions on Nuclear Science, 1999
High leakage currents and incomplete charge collection limit the performance of detectors obtained from bulk semiinsulating (SI) GaAs. In this contest, a crucial role is played by the electron limiting contact. We have investigated the effect of an epitaxial p-type layer deposited on the semi-insulating substrate in place of the usual Schottky contact. Electrical characterization evidences an effect of the p-layer only at low voltages, but radiation detection experiments show an improvement of the charge collection efficiency, which is function of the doping level of the p-layer. In particular both a and x irradiations give evidence of gain mechanisms in the collected charge. From these results, the strong relation between the structure of the electron-blocking interface and the charge collection properties of these detectors comes out.