Infrared photoconductivity of InGaAs/GaAs heterostructures with quantum dots

Abstract

A new variant of fabricating of heterostructures with InAs quantum dots for infrared photodetectors by metalorganic chemical vapor deposition is discussed. A distinctive feature of the growth process is alternation of low and high temperature during growth of GaAs barrier layers. Sandwich structures with high density of quantum dots with high "aspect ratio" value have been grown by use of increased time of quantum dots growth. In these structures photoconductivity near to 4.5 μm is observed up to 200K. Responsitivity is O.5A/W at a temperature of 90K, detectivity is 3*109 cmHz1/2W-1. Peculiarities of lateral infrared photoconductivity and electron transport in heterostructures with quantum dots and the two-dimensional electron channel connected with change in the mobility of 2D electrons caused by photoionization of quantum dots are shown. The first observation of the lateral intraband infrared photoconductivity in non-doped structures at additional photoexcitation as well as lateral interband photoconductivity in the range 1-2.7 μm at room temperature is reported.