| 1. |
- Buyanova, Irina, 1960-, et al.
(author)
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Origin of bandgap bowing in GaNP alloys
- 2004
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In: IEE Proceedings - Optoelectronics. - : Institution of Engineering and Technology (IET). - 1350-2433 .- 1359-7078.
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Conference paper (peer-reviewed)abstract
- By employing photoluminescence excitation (PLE) spectroscopy, the authors provide direct evidence for N-induced strong coupling and repelling of host conduction band (CB) states in GaNxP1-x. This strong coupling is manifested as (i) a drastic change in the ratio of oscillator strengths between the optical transition near Eg/rGamma and that near the CB minimum (CBM); (ii) a strong blue shift of the a1(Γ) state with increasing N composition accompanying a red shift of the CBM; (iii) pinning of the energies of the N-related levels; and (iv) the appearance of t2(L) or t2(X3) upon N incorporation of which the energy position is insensitive to N compositions. These findings shed new light on the controversial issue of the dominant mechanism responsible for the giant bandgap bowing of dilute nitrides.
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| 2. |
- Chen, Weimin, 1959-, et al.
(author)
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Defects in dilute nitrides : significance and experimental signatures
- 2004
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In: IEE Proceedings - Optoelectronics. - Optoelectronics, IEE Proceedings, Vol. 151, Issue 5 : IET. - 1350-2433 .- 1359-7078.
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Conference paper (peer-reviewed)abstract
- A brief review of experimental results of defects in dilute nitrides studied by various techniques reported so far in the literature is given. The emphasis is on experimental signatures of grown-in defects in Ga(In)NAs and Ga(Al)NP, which are expected to play important roles in device performance and in determining the success of this novel material system for applications in optoelectronics. The authors' recent results from optically detected magnetic resonance studies of grown-in intrinsic defects, i.e. AsGa antisite in Ga(In)NAs and Ga self-interstitials in Ga(Al,In)NP, are discussed in more detail, in an effort to provide detailed information on the chemical identification and the formation mechanism of the defects as well as to reveal their role in degrading the optical quality of the materials. The review aims not only to provide an overview of the present knowledge and understanding of defects in dilute nitrides, but also to stress the urgent need for concerted efforts to positively identify the most important defects that are harmful to device performance and to design strategies to suppress them during growth or to eliminate them by post-growth treatments.
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| 3. |
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| 4. |
- Izadifard, Morteza, 1965-, et al.
(author)
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Effects of rapid thermal annealing on optical quality of GaNP alloys
- 2004
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In: EMRS-2004 Spring Meeting,2004. - : Institution of Engineering and Technology (IET). ; , s. 335-
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Conference paper (peer-reviewed)abstract
- Significant improvements in radiative efficiency of GaNP epilayers grown on GaP substrates by solid-source molecular beam epitaxy (MBE) are achieved by post-growth rapid thermal annealing (RTA). From temperature-dependent CW and time-resolved photoluminescence (PL) spectroscopies combined with PL excitation measurements, the observed improvements are attributed to annealing out of competing nonradiative centres. This conclusion is supported by the following experimental evidence: reduced thermal quenching of the PL intensity resulting in a substantial (up to 18 times) increase at room temperature (RT) after RTA, and simultaneous improvements in carrier lifetime at RT deduced from time-resolved PL measurements.
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| 5. |
- Krotkus, A., et al.
(author)
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Be-doped low-temperature-grown GaAs material for optoelectronic switches
- 2002
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In: IEE Proceedings - Optoelectronics. - : Institution of Engineering and Technology (IET). - 1350-2433 .- 1359-7078. ; 149:3, s. 111-115
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Journal article (peer-reviewed)abstract
- Structural, electrical and recombination properties of Be-doped low-temperature MBE grown (LTG) GaAs have been investigated by using a number of different experimental techniques. These properties were analysed with respect to the applications of LTG GaAs in ultrafast optoelectronic devices. It has been found that a moderate Be-doping improves the structural quality of the layers and does not affect their semi-insulating behaviour. Electron and hole capture cross-sections, critical parameters for the design of optoelectronic devices from LTG GaAs, equal to sigma(n) = 1.1 x 10(-13) and sigma(p) = 1.8 x 10(-15) cm(2) were also determined.
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| 6. |
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| 7. |
- Oelmann, Bengt, et al.
(author)
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Robust window discriminator for photon-counting pixel detectors
- 2002
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In: IEE Proceedings - Optoelectronics. - : Institution of Engineering and Technology (IET). - 1350-2433 .- 1359-7078. ; 149:2, s. 65-69
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Journal article (peer-reviewed)abstract
- The paper proposes a robust and area-efficient way of designing window discriminators for photon-counting pixel detectors. For that, an all-digital window discriminator is proposed. It is event-driven and does not rely on any external or internal timing references, which makes it possible to use it over a wide range of specifications. In addition, it provides an overall area efficient implementation of the digital electronics in photon-counting pixel detectors. The transistor-level implementation of the circuit is presented with its circuit area and timing performance.
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| 8. |
- Ohlen, P., et al.
(author)
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Measurements and modelling of pattern-dependent BER and jitter in reshaping optoelectronic repeaters
- 2000
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In: IEE Proceedings - Optoelectronics. - : Institution of Engineering and Technology (IET). - 1350-2433 .- 1359-7078. ; 147:2, s. 97-103
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Journal article (peer-reviewed)abstract
- A reshaping optoelectronic repeater is investigated in a loop experiment. If such a device is used in an optical network, the jitter accumulation and its influence on the cascadability are important issues. Whereas the RMS jitter was fairly independent for PRBS patterns, the bit-error rate showed a large pattern dependence. In order to explain these results, a simplified model of the repeater is used, where the device is modelled as a filter followed by an ideal limiter.
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