Photoelectric spectroscopy of InAs/GaAs quantum dot heterostructures in a Semiconductor/Electrolyte system

The photovoltaic effect in the semiconductor/electrolyte junction is an eff ective method for investigation of the energy spectrum of InAs/GaAs heteros tructures with self-assembled quantum dots. An important advantage of this method is its high sensitivity. This makes it possible to obtain photoelect ric spectra from quantum dots with high barriers for the electron and hole emission from quantum dots into the matrix even if the surface density of t he dots is low (similar to 10(9) cm(-2)). In a strong transverse electric f ield, broadening of the lines of optical transitions and emission of electr ons and holes from quantum dots into the matrix directly from the excited s tates are observed. The effect of the photovoltage sign reversal was detect ed for a sufficiently high positive bias across the barrier within the semi conductor. This effect is related to the formation of a positive charge at the interface between the cap layer and electrolyte and of the negative cha rge on impurities and defects in the quantum dot layer. (C) 2001 MAIK "Nauk a /Interperiodica".