Design and fabrication of zinc oxide multilayers light emitting devices

Abstract

Chapter 2 Literature Review CJapter 2 LlTERATURE REVIEW 2.1 Zinc Oxide ZnO has gained substantial interest in semiconductor research because o f its wide band gap (-3.4eV) and also its large exciton binding energy (-60meV). These made ZnO a favorable candidate for UV semiconductor laser, especially for room-temperature operation. As such, we have chosen ZnO as our platform for random lasers studies in this thesis. Researches on ZnO can be traced back to many decades. Material characterizations such as lattice parameters were investigated as early as 1935 [2 8 ,2 9 ,3 0 ,3 1 ,3 2 ,3 3 ] A J s o^ 0 ptical properties and processes in ZnO were studied intensively. [34'35,36,37'38'391 One of the main reasons that attracted attentions to ZnO is because o f its large exciton binding energy, which paves the way for an intense near band edge excitonic emission at room or even higher temperature. This is because the binding energy is almost 2.4 times larger than the thermal