Self-assembled semiconductor structures: Electronic and optoelectronic properties

Strained epitaxy has been shown to produce pyramidal-shaped semiconductor dot structures by single-step epitaxy, The very high density of these dots (approaching teradots per wafer) and their ever improving uniformity suggest that these features could have important applications in future microelectronics. Understanding the structural and electronic properties of these quantum dots is therefore of great importance. In this paper, we examine some of the physics controlling the performance of devices that could be made from such structures. The self-assembled quantum dots are highly strained and we will examine the strain tensor in these quantum dots using a valence force-field model. In this paper we will address the following issues, 1) What is the general nature of the strain tensor in self assembled quantum dots? 2) What are the electron and hole spectra for InAs-GaAs quantum dots? 3) What are the important intersubband radiative and nonradiative scattering processes in the self assembled quantum dots? In particular, we will discuss how the electron-phonon interactions are modified in the quantum dot structures. Consequences for uncooled intersubband devices such as lasers, detectors, and quantum transistors will be briefly discussed.