N. V. Baidus

We demonstrate the feasibility to obtain electroluminescence (EL), up to room temperature, from self‐assembled quantum dots included in a Schottky diode. Moreover, using a ferromagnet as the contact layer, sizable circular polarization of the emission in the presence of an external magnetic field (B) is obtained. A resonant behavior of the degree of circular polarization as a function of applied voltage, for a given B, is observed. We explain our findings using a model including tunneling through the metal‐semiconductor interface, transport in the near surface region of the heterostructure and out‐of‐equilibrium statistics of the injected carriers.

The authors demonstrate efficient hole spin injection from a ferromagnetic metal (Ni) contact in a forward biased light emitting Schottky diode (LESD) fabricated on a GaAs based heterostructure with a quantum well (QW). The spin polarization of the injected holes was detected by measuring the circular polarization of the electroluminescence (EL) from the near surface InGaAs∕GaAs QW. An intermediate gold layer has been used in order to improve the spin injection efficiency. Over 40% degree of circular polarization of the EL has been observed at T=2K for the LESD structure with Au–Ni–Au Schottky contact.

We show the usefulness of the photovoltage (PV) spectroscopy in the semiconductor-electrolyte system for probing the electronic effects of the ordering. We compare photo-e.m.f. spectra measured for an electrolyte Schottky contact made on InGaP layers with different degree of order, to results obtained by using other spectroscopy techniques, namely, photoluminescence (PL) and planar photoconductivity (PC) measurements.

A comparative study of the surface morphology, photoluminescence, and photoelectric spectra of heterostructures with InAs/GaAs quantum dots (QDs) grown on the surface, uncovered by etching away the cladding layer, and built in the GaAs matrix is reported. The red-shift of the ground transition energy in the surface QDs compared to the built-in ones has been shown to be related not only to relaxation of the elastic strain, but also to the differences in size, shape, and chemical composition of the nanoclusters. The method of photoelectric spectroscopy in a semiconductor/electrolyte system has been applied to monitor the process of etching of the cladding layer in situ. Using this method, controlled uncovering of the buried QDs was shown to be possible. In turn, this makes it possible to study the actual morphology of the buried quantum-size layers by atomic force microscopy.