Optical properties of photodetectors based on wurtzite quantum dot arrays

Abstract

We show that two types of wurtzite quantum dots can be grown with the C3v symmetry. Their symmetry axis coincides with a threefold proper rotation and a 63 improper rotation axis of the wurtzite lattice, respectively. One-, two-, and three-dimensional periodic structures made of such dots are considered. Most of them have the C3v point symmetry except some one- and three-dimensional structures that have the C6v one. The symmetry planes and possible glide planes for the dots and dot structures are those of the wurtzite matrix. It is shown that, under incident light propagating along the growth direction, the absorption is strong for valence-to-conduction-band transitions but, on the contrary, the absorption is weak in infrared detectors based on transitions within the conduction band. It makes it necessary to draw a grating to change the light direction within the device (as is also the case for infrared detectors based on wurtzite quantum wells or superlattices). © 2008 The American Physical Society.