Photoluminescence characterization of n-on-p Hg1−xCdxTe photodiodes formed by ion-milling technique shows that the luminescence peak of the n-type conversion region shifts remarkably toward higher energy with an amount of ∼40meV more than that of the p region. The photovoltaic response of the diodes was examined. The origin of the “blueshift” may be ascribed to the Burstein-Moss effect associated with the high electron concentration of the type conversion region.

The effects of thermal annealing on the interfaces of InGa(N)As/GaAs single quantum wells (SQWs) are investigated by excitation-, temperature-, and magnetic field-dependent photoluminescence (PL). The annealing at 750 C results in more significant blueshift and narrowing to the PL peak than that at 600 C. Each of the PL spectra can be reproduced with two PL components: (i) the low-energy component (LE) keeps energetically unchanged, while the high-energy component (HE) moves up with excitation and shows at higher energy for the In 0.375 Ga 0.625 As/GaAs but crosses over with the LE at a medium excitation power for the In 0.375 Ga 0.625 N 0.012 As 0.988 /GaAs SQWs. The HE is broader than the corresponding LE, the annealing at 750 C narrows the LE and HE and shrinks their energetic separation; (ii) the PL components are excitonic, and the InGaNAs shows slightly enhanced excitonic effects relative to the InGaAs SQW; (iii) no typical S-shape evolution of PL energy with temperature is detectable, and similar blueshift and narrowing are identified for the same annealing. The phenomena are mainly from the interfacial processes. Annealing improves the intralayer quality, enhances the interfacial In-Ga interdiffusion, and reduces the interfacial fluctuation. The interfacial interdiffusion does not change obviously by the small N content and hence similar PL-component narrowing and blueshift are observed for the SQWs after a nominally identical annealing. Comparison with previous studies is made and the PL measurements under different conditions are shown to be effective for probing the interfacial evolution in QWs.

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Modulation of built-in surface electric field was well established as a mechanism of photoreflectance (PR) processes in bulklike semiconductors, though pump light induced excess carrier concentration was once suggested theoretically as another possibility. In this work, pump power dependent infrared PR measurements were carried out on two arsenic-doped narrow-gap HgCdTe epilayer samples in a wide power range from about 1 mW to up to 480 mW. The relation between the integral intensity I of main PR features and pump power P can be described with I∝Pk, and the k is sensitive to temperature and pump power. While it takes a value of about 0.5 at 11 K or under considerably high pumping power at 77 and 150 K, it is close to 1.0 in a low pump power range at 77 and 150 K. The modulation mechanism is indicated as a combination of the modulation of built-in surface electric field and the pumping induced excess carrier concentration near the band edge. The modulation of built-in surface electric field takes place when the Debye screening length is larger than the pump light penetration depth, otherwise the pumping induced excess carrier concentration also comes into force. High pump power significantly enhances the signal and improves the signal-to-noise ratio of PR spectrum especially when the pumping induced excess carrier concentration plays a dominant role and can, therefore, serve as a primary choice for performing infrared PR measurements on narrow-gap HgCdTe epilayers efficiently.