Photoluminescence of phosphorus atomic layer doped Ge grown on Si
Yuji Yamamoto (Innovations for High Performance Microelectronics)
Li Wei Nien (Innovations for High Performance Microelectronics)
Giovanni Capellini (University of Roma Tre, Innovations for High Performance Microelectronics)
Michele Virgilio (University of Pisa)
Ioan Costina (Innovations for High Performance Microelectronics)
Markus Andreas Schubert (Innovations for High Performance Microelectronics)
Winfried Seifert (Innovations for High Performance Microelectronics)
Giordano Scappucci (Kavli institute of nanoscience Delft, TU Delft - QCD/Scappucci Lab, TU Delft - QuTech Advanced Research Centre)
Diego Sabbagh (TU Delft - QCD/Scappucci Lab, Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre)
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Abstract
Improvement of the photoluminescence (PL) of Phosphorus (P) doped Ge by P atomic layer doping (ALD) is investigated. Fifty P delta layers of 8 ×1013 cm-2 separated by 4 nm Ge spacer are selectively deposited at 300 °C on a 700 nm thick P-doped Ge buffer layer of 1.4 × 1019 cm-3 on SiO2 structured Si (100) substrate. A high P concentration region of 1.6 × 1020 cm-3 with abrupt P delta profiles is formed by the P-ALD process. Compared to the P-doped Ge buffer layer, a reduced PL intensity is observed, which might be caused by a higher density of point defects in the P delta doped Ge layer. The peak position is shifted by ∼0.1 eV towards lower energy, indicating an increased active carrier concentration in the P-delta doped Ge layer. By introducing annealing at 400 °C to 500 °C after each Ge spacer deposition, P desorption and diffusion is observed resulting in relatively uniform P profiles of ∼2 × 1019 cm-3. Increased PL intensity and red shift of the PL peak are observed due to improved crystallinity and higher active P concentration.