Studies of photocarrier relaxation processes in polysilane alloys from subpicosecond to metastability

• Published in: Journal of non-crystalline solids 1992, Vol.141 (1-3), p.66-75
• Main Authors: Vardeny, Z.V., Wei, X., Hess, B.C., Han, S.G., Nitta, S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Inorganic and organomineral polymers; Physicochemistry of polymers; Properties and characterization
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/S0022-3093(05)80520-4

The photocarrier relaxation processes in polysilane alloys, a-Si:H/a-(SiH 2) n , have been studied using the picosecond transient and cw photomodulation (PM) techniques and light-induced ESR. For below gap excitation, the picosecond decay is exponential with an increasing decay rate at lower temperatures. This is interpreted in terms of e-h geminate recombination in the small clusters (≈ 10 Å) of a-Si:H embedded in the polysilane matrix. The cw PM spectrum contains a single photoinduced-absorption band, which is interpreted as due to photocarriers trapped in dangling bond (DB) defects. This interpretation is based on the temperature and excitation intensity dependencies, as well as on the reduction of the ESR signal under illumination. From the analysis of the DB optical transitions, the DB effective correlation energy U eff = 0.3 eV and its relaxation energy Δ E r = 0.4 eV are estimated.