Prozessierung und optische Charakterisierung einzelner InGaN/AlGaN-Quantenpunkte unter Berücksichtigung der internen Felder

Abstract

Nitride-based semiconductor quantum dots (QDs) have emerged in the past decade as important materials due to their application in optoelectronic devices, such as light emitting diodes and laser diodes. Furthermore, For quantum-information-processing applications, they open a new spectral region of blue and ultraviolet for single-photon sources. InGaN QDs are promising candidates to realize single-photon emission at elevated temperatures due to their large band gap and high excitonic binding energies. For technological applications it is favorable to achieve single-photon emission in the short-wavelength range operating near room temperatures. For the realization of this by self-assembled InGaN QDs an increas of the carrier confinement in the QDs is necessary. In order to increase the carrier confinement in the QDs a promising concept is to sandwich the QDs between additional barriers with a higher band gap. In this thesis an investigation of the optical properties of InGaN/AlGaN QDs realized by the concept of a barrier layer is discussed. In addition the electronic properties of these QDs, like their strong internal electric field is analyzed. The quantum-confined Stark effect in the presence of the strong internal field affects the confinement of the carriers in the QDs. In order to investigat the optical properties of the InGaN QDs and to realize single-photon emission at elevated temperatures, a thorough investigation of the internal electric field is given in this thesis. Furthermore, the influence of the internal field on the localization of the carriers by applying an external electric field is discussed. By using nanosphere lithography is a compact structure processed, which was used for optoelectronic investigation of the single InGaN QDs by changing the exteral internal fields. Generally, it is showed that the compensation of internal fields in InGaN QD systems is of considerable importance to achieve strong single-quantum-dot emission line at elevated temperature.