Low pressure chemical vapour deposition at quasi-high flow

A new chemical vapour deposition (CVD) technique is presented. It is especially advantageous for the deposition of compound materials. The technique improves the uniformity and reproducibility of the deposition. The economical use of gaseous reactants is improved by a factor varying between 5 and 20. This is important in the case of expensive metal-organic CVD methods. The method consists in the manifold repetition of the following sequence: evacuation, filling and deposition in a horizontal tube reactor. The filling time of 50 ms is short compared with the deposition period 1 s.\ud \ud The advantages of the method are demostrated with results for the deposition of undoped, phosphorus-doped and boron-doped silicon and SiO2.\u

Low-Pressure CVD of Germanium-Silicon films using Silane and Germane sources

In this work a study of Low Pressure Chemical Vapour Deposition (LPCVD) of Germanium-Silicon films has been carried out. The films were deposited on thermally oxidised silicon wafers using a horizontal hot-wall LPCVD system, at deposition temperatures ranging from 430 to 480 oC and total pressures from 3 to 200 Pa. Pure GeH4 and SiH4 gas sources were used for the experiments. Growth kinetics and texture of GexSi1-x films versus varying deposition conditions, resulting in different film properties, were investigated. The effect of Germanium content in the layers on deposition rate at 430 oC and the change in the film crystallinity caused by deposition at different deposition pressures were studied

TFTs as photodetectors for optical interconnects

In this work we are looking at the prospect of using poly-silicon based Thin Film Transistors (TFTs) as photodetectors for optical interconnects that can detect light effectively at 1100nm wavelength from silicon based Light Emitting Diodes (LEDs). These TFTs were fabricated from laser crystallized silicon and were characterized under darkness and illumination. The photosensitivities of these devices were limited due to the presence of aluminium as their gate electrode but have shown us the possibility of a new approach to photodetection

The effect of dislocation loops on the light emission of silicon LEDs

Recently, different and apparently contradicting results were published regarding the influence of crystal defects on the light emission efficiency of silicon LEDs at room temperature (Wai Lek Ng). In this paper we report our results on light emission of silicon p/sup +/n diodes with various defect engineering approaches. The p/sup +/ region was formed either by ion implantation or by diffusion; and optionally, additional lattice damage was created by silicon ion implantation. The experiments clearly indicate that lattice defects have a detrimental effect on light emission, contrary to the results published in recent years

Influence of interface recombination in light emission from lateral Si-based light emitting devices

The influence of interface recombination on the electroluminescence profile of a lateral p+/p/n+ light emitting diode fabricated on Silicon On Insulator (SOI) materials has been experimentally investigated. Our device resembles a MOSFET fabricated on SOI (1), except that the source region has opposite doping to the drain. By controlling the voltage bias at the poly gate on top of active emitting region in association with a bias on the silicon substrate under the active region we were able to diminish the non-radiative recombination component at Si/SiO2 interface and therefore enhance the radiative recombination in the thin film SOI. When the diode is working under constant current condition, we observe an increased light output of ~ 20 % as the gate and/or the substrate are biased negatively. The intensity profile across the device is also strongly influenced. To understand the device thoroughly, the structure has also been simulated showing agreement with experimental results.\u

Influence of dislocation loops on the near infrared light emission from silicon diodes

The infrared light emission of forward-biased silicon diodes is studied. Through ion implantation and anneal, dislocation loops were created near the diode junction. These loops suppress the light emission at the band-to-band peak around 1.1 μm. The so-called D1 line at 1.5 μm is strongly enhanced by these dislocation loops. We report a full study of photoluminescence and electroluminescence of these diodes. The results lead to new insights for the manufacturing approach of practical infrared light sources in integrated circuit