Planar devices

Another advantage of the micro-LC approach is that the required sample size is minimal, so the sample can be drawn from a 1-1 laboratory scale reactor without influencing the reactor composition. The ISCO pLC-500 microflow syringe pump has proven to be reliable and reproducible in evaluations in our laboratory. Capillary liquid columns have been fabricated on planar devices such as silicon to form a miniaturized separation device.19... 

Ion implantation appears as the only feasible method to accomplish selective area doping of SiC in planar device technology. As described in this chapter, substantial progress has been made during recent years but several fundamental issues and technology barriers remain before the implantation process is fully developed and can be truly implemented in SiC device processing. Eor instance, mesa-etched p n-diodes... 

The thermal oxidation process is an essential feature of planar-device fabrication and plays an important role in the diffusion of dopants in Si. In the thermal oxidation process, Si reacts with either oxygen or water vapor at temperatures between 600 and 1250 °C to form Si02. The oxidation reaction may be represented by the following two reactions ... 

For biosensor devices these problems are aggravated because of the additional integration of a biological component on a planar device surface [50]. 

Figure 8.14 Planar device in which reservoirs are affixed to the chip following bonding of the two plates, and no holes are drilled into the top plate. The large circle represents the coverslip, and the smaller circles represent the reservoirs. (Reprinted from Ref. 55 with permission.)...

Figure 8.15 Simple planar device for CE. (Redrawn from Ref. 54 with permission.)...

The work reported in this chapter appears to indicate that these and larger values for the reduction of the absorber thickness can indeed be realised with inexpensive substrate and absorber materials. Given the early stage of this research and the as yet limited theoretical understanding of non-planar devices of this kind, the emphasis in this chapter will be on experimental results and qualitative concepts. 

One of the basic challenges in the fabrication of highly non-planar devices lies in the preparation only a few methods have so far been explored to produce deeply structured thin films on a flat substrate and—in a second step—to produce a continuous coverage on a deeply structured substrate. In Section 6.3, some of the possible fabrication processes will be discussed. 

While purity, crystallinity and defect densities are not always optimal in depositions laid down by inexpensive methods, non-planar devices with energy conversion efficiencies of np to 5% have now been demonstrated. This development confirms the initial expectation that new device geometries may indeed open a broader materials development. Moreover, recent developments in photovoltaics may spin-off into other electronic applications, such as transistor, sensor and LED development. 

This indicates that the switching process is not a bulk effect but located in the vicinity of the contacts. However, from this experiment we could not determine if switching happens at the positively or negatively biased contact. Planar devices with two Au contacts did not show switching but only a slightly non-linear behaviour. 

Furthermore, we have extended the planar device structure to localise the interface where the switching appears. An additional contact stripe was located in the gap between the existing two metal contact stripes. In this case, the distance between the two parallel metal contacts was 15 pm. The middle electrode was positioned between them and had a width of 5 pm. The contacts were covered with Cu(TCNQ) by complete conversion of a previously deposited Cu layer. 

Processing techniques for thermally grown oxides and nitrides can be incorporated into existing planar device technology. 

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