No abstract

The near-field propagation behavior of terahertz (THz) pulses generated by a planar large-aperture photoconducting THz transmitter has been characterized. A simulation model based on Huygens-Fresnel diffraction theory has been developed that permits accurate prediction of the spatiotemporal profiles of the THz beam everywhere and gives excellent agreement with experimental measurements. Two key conclusions emerge from this research, namely, the realization that for practical laboratory setups one is always working in the near-field regime and that the proper temporal shape of the THz field at the antenna is one that rises rapidly but decays slowly.

No abstract

Depth profiling of ultrashallow B implants in silicon using a magnetic-sector secondary ion mass spectrometry instrument J.The Carrier Illumination™ ͑CI͒ method is an optical technique for nondestructive in-line monitoring of postanneal junction depth, preanneal preamorphization implant depth, and dose. This work intends to extend the use of the CI measurements from a relatively process specific quantitative measurement towards a more universal quantitative analysis of junction depth, profile abruptness, and implant dose. For that purpose the predictive capabilities of the present physical models with respect to the quantitative dependence of the CI signal on the applied generation power is investigated for a wide variety of samples, including bulk material, highly abrupt chemical vapor deposition grown ͑B͒ structures, and implanted ultrashallow junctions ͑B, BF 2 , As͒. In general, the CI signal may arise from a combination of three components: a primary one originating from the reflection of the probe laser beam from the dopant profile depth corresponding with the injected excess carrier level, in some cases, from reflection from near-surface carriers, and in other cases, from residual damage within the doped region.

No abstract