Doped silicon films electrical resistivity

The solution-processed doped silicon films described above (baked at 500 °C for 2 hr) exhibited high electrical resistivity (greater than 300 Qcm), which is the measurement limit of the instrument we used. To lower the resistivity, we tried an additional rapid thermal annealing (RTA) of the film prepared from the copolymerized solution with 1 wt% phosphorus concentration. In this RTA, the SiC plate on which the sample was placed was irradiated with infrared (IR) light from a 1-kW IR lamp. The RTA conditions were 600 °C for 2 hr, 650 °C for 20 min, 700 °C for 5 min, and 750 °C for 5 min these temperatures were that of the SiC plate, and the temperature of the Si film is estimated to be several dozens of degrees lower than that. 

In addition to silicon and metals, a third important element being deposited as thin films is diamond (Celii and Butler, 1991 May, 2000). For many years, diamonds were synthesized by a high pressure/high temperature technique that produced bulk diamonds. More recently, the interest in diamonds has expanded to thin films. Diamond has a slew of properties that make it a desired material in thin-film form hardness, thermal conductivity, optical transparency, chemical resistance, electrical insulation, and susceptibility to doping. Thin film diamond is prepared using chemical vapor deposition, and we examine the process in some detail as a prototypical chemical vapor example. Despite its importance and the intensity of research focused on diamond chemical vapor deposition, there remains uncertainty about the exact mechanism. 

Critical properties of TCO coatings are electrical resistance and transparency [3], but for solar cell applications very often texture and large haze factors, i.e., ratio of diffuse to total transmission, have similar importance. Large haze factors have been shown to influence positively the efficiency of silicon solar cells, because the reflection at the TCO-silicon interface is reduced and the scattering increases the pathway of light inside the active material. The preparation and characteristics of several TCO materials have been reviewed by Chopra et al. [92] and Dawar and Joshi [93]. The optical and electrical properties of ITO and aluminum doped zinc oxide have been studied in detail by Granqvist and coworkers [94, 95], but these films were prepared by sputtering and not by CVD. Very recently they also published an overview of transparent conductive electrodes for electrochromic devices [7]. 

The samples were fabricated on a bonded SOI wafer with a 60-70 tun thick SOI film, where the buried-oxide layer was 400 mn thick. The wafer was heavily doped with phosphorous 3.5 - 16 TO cm. The electrons were uniformly heated in the very long (up to 1500 pm) SOI film by applying heating current between the contacts, which were at the ends of the silicon film. The Joule heat was calculated by using the values of the sheet resistance of the film and of the electrical current. A He/" He dilution refrigerator was used for the measvuement in the temperature range between 50 mK and 500 mK. 

Detailed reports of n-type Si-doping of AlxGai.xN were also limited until recently. Details of the electrical and other properties of these doped films are usually limited to a few selected carrier concentrations and alloy compositions. Murakami et al [10] achieved Si-doping of Alo.1Gao.9N by MOVPE with carrier concentrations of 6 x 1017 and 2 x 101 cm 3, with mobilities (calculated from resistivity data) of 40 and 180 cm2/V s. Khan et al [11] also demonstrated MOVPE growth of Alo.09Gao.91N doped with silicon. Hall-effect measurements of these films revealed a mobility of 35 cm2/V s and a donor concentration of 5 x 101 cm 3. 

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