Electroluminescence in quantum well heterostructures p‐Al_xGa_1–xAs/GaAs_1–yP_y/n‐Al_xGa_1–xAs under uniaxial stress

Abstract

This article summarizes some of the key findings of a report (HM Inspectorate of Probation, 1998) of an inspection of the work of the probation service in England and Wales with sex offenders. The inspection took place at a time of unprecedented public debate and concern about the nature and impact of sexual offending, but this focused attention on a few high‐profile individuals rather than the majority of sexual offenders who assaulted victims that were known to them. For the purposes of the inspection, 10 probation areas were visited at the beginning of 1997 and a similar inspection programme was followed in each area, comprising observation of group work, examination of over 300 pre‐sentence court reports, a similar number of case files on offenders subject to supervision on probation orders and following release from prison and interviews with probation staff and representatives from a variety of other agencies. Although there had been research relating to community‐based probation programmes previously in this country, this concentrated on group work programmes, which, in reality, are attended by a minority of sex offenders under supervision. This inspection examined and assessed for the first time a far broader spectrum of the work of probation officers with sex offenders. Copyright © 1998 John Wiley & Sons, Ltd.

TM/TE polarization tuning and switching in tensile strained p-AlGaAs/GaAsP/n-AlGaAs heterostructures by uniaxial compression

“…Tomm et al [20] have shown experimentally that such pristine devices are essentially uniaxially compressed along the [110] direction; the initial average device compression in the center of the laser bar was determined to about −0.16% for a standard indium soldering process on a copper heat sink, whereas the packaging-induced strain for AuSn mounting on CuW is smaller by one order of magnitude [21]. We have observed a blue shift of the EL spectrum by about 25 meV under uniaxial compression of P=5 kbar on our samples with 0.55 mm cavity [3] that corresponds to a reduction of the in-built tensile strain by about −0.19%. This reduction was calculated as described in [4,15] and is confirmed by the agreement between the calculated change of the optical gap and the observed blue shift of the EL spectrum under uniaxial compression [4].…”

“…The compressive or tensile strained III-V layered heterostructures with quantum wells (QW), which are the main functional materials for semiconductor laser diodes and other optoelectronic devices, offer unprecedented flexibility for band structure engineering [1]. They are highly sensitive to external hydrostatic [2] and uniaxial [3] compression. Under [110] uniaxial compression (P≈5 kbar), the electroluminescence (EL) spectrum in p-Al 0.45 Ga 0.55 As/ GaAs 0.84 P 0.16 /n-Al 0.45 Ga 0.55 As laser diodes demonstrates a blue shift up to 25 meV [3].…”

“…They are highly sensitive to external hydrostatic [2] and uniaxial [3] compression. Under [110] uniaxial compression (P≈5 kbar), the electroluminescence (EL) spectrum in p-Al 0.45 Ga 0.55 As/ GaAs 0.84 P 0.16 /n-Al 0.45 Ga 0.55 As laser diodes demonstrates a blue shift up to 25 meV [3]. According to the numerical calculations [4], even more dramatic changes should take place under uniaxial compression in correlation between transverse electric (TE) and transverse magnetic (TM) polarization modes of emitting light.…”

Effect of uniaxial stress on electroluminescence, valence band modification, optical gain, and polarization modes in tensile strained p-AlGaAs/GaAsP/n-AlGaAs laser diode structures: Numerical calculations and experimental results

“…In particular, metal-insulator transitions were investigated under uniform pressure in bulk 1 and low-dimensional 2 materials, and a range of electronic topological transitions under uniaxial compression were detected. 3 Recently, the possibility of laser diodes wavelength tuning by means of uniaxial stress 4 and uniform compression in hydrostatic pressure cells 5 has been successfully demonstrated.…”