Highly accurate resistances can be made by iterative laser-induced local diffusion of dopants from the drain and source of a gateless field effect transistor into its channel, thereby forming an electrical link between two adjacent p-n junction diodes. In this paper we present a complete modeling, which permits to obtain the device characteristics from process parameters. Three-dimensional (3D) temperature calculations are performed from heat diffusion equation using an apparent heat capacity formulation. Melted region determinations are satisfactory compared with in-situ real-time optical measurements of the melted region behavior. Then 3D dopant diffusion profiles are calculated using Fick’s diffusion equation. Finally electronic characteristics are obtained from the new tube multiplexing algorithm for computing the I-V characteristic and the device differential resistance. Numerical simulations using our software are satisfactory compared with experimental I-V measurements.
Germanium wafer surface is modified by a technique of CO2-laser induced air breakdown processing, which was recently introduced and used to produce photoluminescent Si-based nanostructured layers. Structural and optical properties of the Ge-based layers, formed under the irradiation spot as a result of the processing, are characterized by different techniques (SEM, XPS, FTIR, XRD, and PL). It has been found that the layers present a porous structure, containing nanoscale holes, and consist of Ge nanocrystals embedded into GeO2 matrices. They exhibited strong photoluminescence (PL) in the green range (2.2 eV), which was attributed to defects in GeO2 matrix due to the presence of Ge-O modes with some OH vibration in the FTIR spectra. The layers are of importance for local patterning of nanostructures on semiconductors.