Interlacing quantum dot- and defect-formation in group-IV materials for optoelectronic applications
Sprache des Vortragstitels:
E-MRS Fall Meeting 2019
Sprache des Tagungstitel:
The search for efficient group-IV-based light emitters that preserve their optical properties well above room-temperature (RT) and that can be fabricated on Si is ongoing. For integration on Si-platforms, electrical charge carrier injection and convenient coupling to other Si photonic components are clearly essential. Epitaxial quantum dots (QDs) offer benefits of quantum confinement and all-crystalline matrix material, important for doping of e.g. LEDs. We introduce a new class of group-IV light-sources consisting of epitaxial Ge/Si QDs into which intentionally extended point defects are introduced upon low-energy ion-implantation. For such defect-enhanced quantum dots (DEQDs) the charge carriers are confined inside the QD by two interlaced zero-dimensional structures. Holes experience quantum confinement due to the large bandoffsets between Si and Ge, while electrons are trapped by introduced defects for which the split- self-interstitial was found to be a configuration with minimum formation energy. Prominent features of DEQDs are clear signs for optically-pumped lasing, absence of thermal quenching of the light-emission up to RT, and the demonstration of LEDs, grown directly on Si without that need of thick buffer layers that exhibit at 100°C still ~30% of their maximum emission. Nevertheless, in view of the intriguing but poorly explored DEQD-properties and the perspectives of using them for Si-photonics, we discuss strategies towards (1) improvement of their light-emission efficiency, (2) understanding the microstructural nature of DEQDs upon their formation, robustness, optical properties, strain, etc. and (3) fostering the potential of DEQDs concerning devices for Si-based optoelectronics and beyond.