Abstract
In this work, electrically active defects of pristine and 5.5 MeV electron irradiated p-type silicon–germanium (Si1−xGex)-based diodes were examined by combining regular capacitance deep-level transient spectroscopy (C-DLTS) and Laplace DLTS (L-DLTS) techniques. The p-type SiGe alloys with slightly different Ge contents were examined. It was deduced from C-DLTS and L-DLTS spectra that the carbon/oxygen-associated complexes prevailed in the pristine Si0.949Ge0.051 alloys. Irradiation with 5.5 MeV electrons led to a considerable change in the DLT spectrum containing up to seven spectral peaks due to the introduction of radiation defects. These defects were identified using activation energy values reported in the literature. The double interstitial and oxygen complexes and the vacancy, di-vacancy and tri-vacancy ascribed traps were revealed in the irradiated samples. The interstitial carbon and the metastable as well as stable forms of carbon–oxygen (CiOi* and CiOi) complexes were also identified for the electron-irradiated SiGe alloys. It was found that the unstable form of the carbon–oxygen complex became a stable complex in the irradiated and the subsequently annealed (at 125 °C) SiGe samples. The activation energy shifts in the radiation-induced deep traps to lower values were defined when increasing Ge content in the SiGe alloy.
Highlights
Silicon–germanium alloys are promising materials for the fabrication of photocells and powering space applications [1]
SiGe alloys with slightly different Ge content were examined
It was deduced from capacitance deep-level transient spectroscopy (C-DLTS) and Laplace DLTS (L-DLTS)
Summary
Silicon–germanium alloys are promising materials for the fabrication of photocells and powering space applications [1]. The deep carrier traps affect the characteristics of the semiconductor particle detector [10,11] Impurities, such as oxygen and carbon, play an important role in the formation of the irradiation-induced deep traps [12,13,14]. Vacancies and their complexes affect the switching properties of the SiGe-based devices [15,16]. Radiation damage to the Si1−x Gex devices related to the introduction of radiation defects can be “removed” by annealing [17] This can be implemented by the atomic reconfiguration of the crystal structure during material annealing [18]. It was revealed that the carbon–oxygen metastable complexes (Ci Oi * ) were transformed into the stable-state complexes (Ci Oi ) under 125 ◦ C annealing for 15 min of the irradiated samples
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