Potential of hydrogenated microcrystalline silicon-germanium for low thermal budget near infrared sensors
Résumé
Microcrystalline Silicon-Germanium (µc-SiGe:H) is a low bandgap material whose optical and electrical properties strongly depend on deposition conditions. In this work, an above integrated circuit (above-IC) [1]-[3] compatible, near infrared (NIR) sensor based on microcrystalline Silicon-Germanium is produced and characterized. The N-I-P photodiode is obtained by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) from a SiH4 + GeH4 + H2 gas mixture. Quantum efficiency measurements reveals a 60 at.% Ge fraction is optimal for a 200 nm thick µc-SiGe:H intrinsic absorber layer. Above this threshold, the degradation in electrical properties prevails on the gain in absorption.
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