Absorption of infrared radiation in silicon

The absorption of 9-11 µm radiation by thin wafers of lightly doped, n-type Si has been measured at several lattice temperatures from 300 to 800 K. The temperature dependence of the absorption coefficient at ?=10.6 µm is extracted from the data and compared with previous measurements and also with recent theoretical models. A novel processing technique is described in which coupling of the CO₂ laser radiation to the Si lattice is significantly enhanced by the simultaneous absorption of radiation from an argon laser.