Optical properties of III-V nanostructures for optoelectronic applications

Introduction                Since the successful development of quantum well lasers in the 1970s, one of the richest areas of application of semiconductor nanostructures is the area of optoelectronics, such as... [ view full abstract ]

Introduction

               Since the successful development of quantum well lasers in the 1970s, one of the richest areas of application of semiconductor nanostructures is the area of optoelectronics, such as lasers and detectors. The most widely used semiconductors for optoelectronic applications are the compounds formed by group III and group V elements. For instance, GaAs and related compounds are mostly used for optical fiber communications, near infra-red and visible light emitting diodes (LEDs) as well as laser diodes. While, GaN and AlGaN are used for LEDs, solid-state lasers and color displays, in the short wavelength range. Furthermore, optoelectronic devices based on novel semiconductor nanostructures are foreseen to revolutionize nowadays technology in terms of superior performance and efficiency, as well as the reduction of costs and material consumption.

Methods

                The use of semiconductor nanostructures integrated in devices is governed by the realization and control of p-n junctions, obtained by p- and n-type doping of the base materials. In addition to n and p-type doping, the semiconductor nanostructure emission can be tuned by incorporating rare earth ions by implantation and post-growth annealing. Doping can be performed by intentionally adding dopants during the growth (in-situ) or after the growth (ex-situ) by diffusion and ion implantation. However, several issues and controversies still need to be investigated in order to access/control semiconductor properties at the nanoscale level.

Results and Discussion

                We present our recent results on semiconductor nanostructures such as: i) AlxGa1-xN (0 ≤ x ≤ 1) nanowires grown by molecular beam epitaxy on Si (111) substrate implanted with europium (Eu) ions and subject to rapid thermal annealing, ii) AlGaN/GaN superlattice-based diode structures grown by metalorganic chemical vapor deposition implanted with two Eu fluences and subject to high temperature and high pressure annealing (Figure 1) demonstrating optical activation of Eu ions, and iii) silicon-doped GaAs nanowires with different nominal silicon doping levels (Figure 2) demonstrating that WZ/ZB polytypism is predominant for the lowest doping level.              

The optical and vibrational properties of these nanostructures, of utmost importance for optoelectronic applications, will be assessed mainly using contactless spectroscopy techniques such as: photoluminescence, photoluminescence excitation, cathodoluminescence and micro-Raman spectroscopy.