Specific heat measurements from 2 to 300 K of hydrogenated amorphous silicon prepared by hot-wire chemical vapor deposition show a large excess specific heat at low temperature, significantly larger than the Debye specific heat calculated from the measured sound velocity. The as-prepared films have a Schottky anomaly that is associated with metastable hydrogen in the amorphous network, as well as large linear and excess cubic term commonly associated with tunneling two-level systems in amorphous solids. Annealing at 200 °C, a temperature that enables hydrogen mobility but not evaporation, irreversibly reduces the heat capacity, eliminating the Schottky anomaly and leaving a reduced linear heat capacity. A non-monotonic dependence on growth temperature and H content is observed in all effects, except for sound velocity, which suggests that the tunneling two-level systems and the Schottky anomaly are associated with atomic hydrogen and require low density regions to form, while so...

中文翻译：

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氢化非晶硅中的两能级体系和生长诱导的亚稳定性

通过热线化学气相沉积法制备的2至300 K氢化非晶硅的比热测量结果显示，在低温下存在大量的过量比热，该比热明显大于根据测得的声速计算出的德拜比热。所制备的薄膜具有与无定形网络中的亚稳态氢有关的肖特基异常，以及通常与在无定形固体中隧穿两能级系统有关的大的线性和过量立方项。在200°C的退火温度下，氢能流动但不能蒸发，因此不可逆地降低了热容量，消除了肖特基异常并降低了线性热容量。除声速外，所有效应均观察到对生长温度和H含量的非单调依赖性，