Hall data on vapor-phase-epitaxial InP doped with Si, S, Sn, and Se and liquid-encapsulated-Czochralski InP doped with Ge are presented for doping levels between 1015 and 1019 cm−3. The results show nearly identical electrical behavior for all n-type dopants but a consistent discrepancy with theoretical mobility calculations, particularly in the doping range 1017–1019 cm−3. A chemical analysis of the sulphur content in layers doped with sulphur shows that all the dopant is electrically active. The reason for the discrepancy with the calculation is discussed in terms of the description of ionized impurity scattering in the presence of a high density of ionized centers. We also emphasize the similarity with GaAs and suggest that our conclusions apply equally to both materials.

blue ballpoint inks sourced from Western Australian retailers were deposited onto commercial copy paper and analysed using diffuse reflectance visible spectroscopy. Principal component analysis showed that while several pens were clearly distinguishable based on their visible spectra alone, others exhibited overlap. Linear discriminant analysis was then used to build a chemometric model for the classification of the inks. Using a separate validation set, 71.7% of spectra were correctly assigned to a specific pen, and a further 16.7% to the correct pen supplier. Analysis of six pen inks stored under different conditions found the inks remained chemically stable for at least two months when stored in the dark. However, two inks exhibited spectral changes within one week under ambient light, and all but one ink displayed changes within two months, resulting in altered predictions using the chemometric model. This may be useful in cases of alleged fraud, where it is suspected that an ink entry may have been altered using the same pen at a later date. Artificial ageing experiments found that both heat and ultraviolet light play a role in the ageing process, and that accelerated ageing using these factors gives a reasonable depiction of short-term ageing under natural conditions.

A detection system for analytical cathodoluminescence (CL) mode scanning electron microscopy (SEM) is described. This incorporates a cold stage, an efficient light collector, a monochromator and a photomultiplier and used the photon counting technique. The efficiency of the component subsystems was optimized and calibrated, and the performance of alternative light collecting and monochromating equipment is compared. The operation of the photon counter is discussed. The digital output of the photon counter was fed into a multichannel scaler and thence to a computer. This was used to correct the observed count rate with the calibrated spectral variations in the performance of the detection system. Spectra obtained at both room temperature and liquid nitrogen temperacure and monochromatic and panchromatic SEM micrographs are given as examples illustrating the value of this technique.The factors governing the performance of the system are discussed. The forms of noise in the signal and in the detection system are described and the means for minimizing, avoiding or correcting for them are dealt with. Sources of spurious signals in the SEM are treated.

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The conditions for the in situ planar etching of (100) indium phosphide in the In/PCl3 system for both hydrogen and nitrogen ambients have been established. Epitaxial layers grown on substrates vapour etched under these conditions show an improved flatness. The electrical properties of silicon and tin doped indium phosphide layers obtained using mixtures of dichlorosilane and stannic chloride in hydrogen are compared with results from sulphur doped material. Both silicon and tin demonstrate a PCl3 concentration dependence and all three dopants demonstrate 77 K Hall mobilities which imply strong compensation when compared with published theoretical calculations