The present contribution reviews the basic principles of the surface photovoltage (SPV) spectroscopy in the metal-insulator-semiconductor operation mode emphasizing on the crucial necessity of combined analysis of the SPV amplitude and phase spectra for the understanding and correct interpretation of the experimental data. Several results are presented obtained by the application of the SPV spectroscopy to semiconductor bulk materials and nanostructures designed for applications in optoelectronic devices. These include: (i) AlAs/GaAs superlattices with GaAs embedded quantum wells for optical emitters, (ii) multilayer structures with InAs/GaAs submonolayer quantum dots for infra-red photodetectors, (iii) Si nanowires for light trapping in solar cells and (iv) dilute nitrides Ga(In)As(Sb)N layers for photovoltaic applications. Valuable information about the investigated materials is obtained such as the optical absorption spectrum defined by the quantum confinement and excitonic effects, the optical transition energies, the effect of surface states on the minority carrier diffusion length, the type of the residual doping in the layers, and the alignment of the energy bands across the structures. It is shown that the SPV spectroscopy is a powerful highly sensitive non-destructive technique for room temperature characterization of various semiconductor materials applied in optoelectronics.

Microphotoluminescence (PL) spectra of a single InAs/GaAs self-assembled quantum dot (QD) are studied under the main excitation of electron-hole pairs in the wetting layer (WL) and an additional infrared (IR) laser illumination. It is demonstrated that the IR laser with fixed photon energy well below the QD ground state induces striking changes in the spectra for a range of excitation energies and powers of the two lasers. For the main excitation above a threshold energy, defined as the onset of transitions between shallow acceptors and the conduction band in GaAs, the addition of the IR laser will induce a considerable increase in the QD emission intensity. This is explained in terms of additional generation of extra electrons and holes into the QD by the two lasers. For excitation below the threshold energy, the carrier capture efficiency from the WL into the QD is suggested to be essentially determined by the internal electric-field-driven carrier transport in the plane of the WL. The extra holes, generated in the GaAs by the IR laser, are supposed to effectively screen the built-in field, which results in a considerable reduction of the carrier collection efficiency into the QD and, consequently, a decrease of the QD PL intensity. A model is presented which allows estimating the magnitude of the built-in field as well as the dependence of the observed increase of the QD PL intensity on the powers of the two lasers. The use of an additional IR laser is considered to be helpful to effectively manipulate the emission efficiency of the quantum dot, which could be used in practice in quantum-dot-based optical switches.

N⁺-GaAs/n-GaInP lattice-matched heterostructures, grown by metalorganic vapour phase epitaxy, have been studied by capacitance-voltage, current-voltage and current-temperature techniques. This allowed the determination of the conduction band offset in three different and independent ways. The value obtained (0.24-0.25 eV) has been verified by photoluminescence and photoluminescence excitation on a 90 AA thick GaAs well in GaInP grown under the same conditions.