4. Quantum Semiconductors: Nanostructures and Quantum Dots

About this Lecture

Lecture

In this mini-lecture, we explore how we can control semiconductor colour and how we can make low-dimensional semiconductors. In particular, we consider: (i) how small nanoscale crystals (on the order of 10^-9) are needed to control semiconductor colour (because in such small structures the electrons and holes are only able to occupy certain quantum energy states in the conduction and valence bands, and when an electron and a hole recombine, the colour of light emitted depends not only on the band gap but also on the electron and hole quantisation energy — this is why changing the size of semiconductor crystals affects the colour of light emitted); (ii) a demonstration illustrating semiconductors made from differently sized crystals, which thus emit different colours of light; (iii) familiar 3-D carbon structures such as diamond, coal, and graphite; (ii) the low dimensional semiconductor, 2-D graphene, which is a single monolayer of graphite; (iii) 1-D carbon nanotubes, which can be made by rolling a sheet of graphene into a tube; (iv) 0-D Bucky balls; and (v) quantum dots, which are 0-D semiconductor nanostructures, that have applications in bioimaging and biolabeling, optoelectronics, and quantum information technology.

Course

In this course Professor Oleg Makarovskiy (University of Nottingham) explores semiconductors and their relevance in the current Information Age. In the first mini-lecture, we introduce the ages of human advancement, from the Stone Age up until the current Information Age, and consider the advancements in computers and information made in the 20th century. In the second mini-lecture, we discuss what a semiconductor is and how you can make one using electrons and ‘holes.’ In the third mini-lecture, we consider how semiconductors can be used to create light of various colours (LEDs) and transform light into electrical energy (solar cells). In the fourth mini-lecture, we explore how we can control semiconductor colour and how we can make low-dimensional semiconductors, such as quantum dots. In the fifth mini-lecture, we focus on understanding diodes and transistors and how these can be used to create microchips used in computers. Finally, in the sixth mini-lecture, we consider the next advancement in our Information Age, quantum information technology, and the role semiconductors play in this new Quantum Information Age.

Lecturer

Oleg Makarovskiy is an Associate Professor in the School of Physics & Astronomy at the University of Nottingham. His research focuses on experimental semiconductor physics, quantum phenomena in semiconductor nanostructures, and their applications in functional electronic and optoelectronic devices.