Zoran Ikonic

Short-wave infrared LEDs from GeSn/SiGeSn multiple quantum wells

Group IV photonics is on its way to be integrated with electronic circuits, making information transfer and processing faster and more energy efficient. Light sources, a critical component of photonic integrated circuits, are still in development. Here, we compare multi-quantum-well (MQW) light-emitting diodes (LEDs) with Ge0.915Sn0.085 wells and Si0.1Ge0.8Sn0.1 barriers to a reference Ge0.915Sn0.085 homojunction LED. Material properties as well as band structure calculations are discussed, followed by optical investigations. Electroluminescence spectra acquired at various temperatures indicate effective carrier confinement for electrons and holes in the GeSn quantum wells and confirm the excellent performance of GeSn/SiGeSn MQW light emitters.

Low Temperature Deposition of High-k/Metal Gate Stacks on High-Sn Content (Si)GeSn-Alloys

(Si)GeSn is an emerging group IV alloy system offering new exciting properties, with great potential for low power electronics due to the fundamental direct band gap and prospects as high mobility material. In this Article, we present a systematic study of HfO2/TaN high-k/metal gate stacks on (Si)GeSn ternary alloys and low temperature processes for large scale integration of Sn based alloys. Our investigations indicate that SiGeSn ternaries show enhanced thermal stability compared to GeSn binaries, allowing the use of the existing Si technology. Despite the multielemental interface and large Sn content of up to 14 atom %, the HfO2/(Si)GeSn capacitors show small frequency dispersion and stretch-out. The formed TaN/HfO2/(Si)GeSn capacitors present a low leakage current of 2 × 10(-8) A/cm(2) at -1 V and a high breakdown field of ∼8 MV/cm. For large Sn content SiGeSn/GeSn direct band gap heterostructures, process temperatures below 350 °C are required for integration. We developed an atomic vapor deposition process for TaN metal gate on HfO2 high-k dielectric and validated it by resistivity as well as temperature and frequency dependent capacitance-voltage measurements of capacitors on SiGeSn and GeSn. The densities of interface traps are deduced to be in the low 10(12) cm(-2) eV(-1) range and do not depend on the Sn-concentration. The new processes developed here are compatible with (Si)GeSn integration in large scale applications.