Electronics property quantum efficiency

Polycrystalline GaN UV detectors have been realized with 15% quantum efficiency [4], This is about 1 /4 of the quantum efficiency obtained by crystalline devices. Available at a fixed price, however, their increased detection range may well compensate their lack in sensitivity. Furthermore, new semiconductor materials with a matching band gap appear as promising candidates for UV detection if the presumption of the crystallinity is given up. Titanium dioxide, zinc sulfide and zinc oxide have to be mentioned. The opto-electronic properties and also low-cost production processes for these compound semiconductors have already been investigated to some extent for solar cell applications [5]. 

If the generation process is characterized by the primary quantum efficiency rj, the transport properties by the mobility /1, and the recombination by the free-carrier liefetime t, the steady-state photoelectric current can in the case of mobile electrons and immobile holes generally be described by Eq. (13) 14> ... 

In conclusion it must be stressed that, for applications of the semiconductor properties of organic dyes and other compounds, the important factors besides the energy gap AE and the primary quantum efficiency r of the generation of electron-hole pairs are the characteristic parameters mobility and lifetime of electrons and holes. 

We have investigated the photocurrent behavior of multilayers of a Chi a-DPL (molar ratio 1/1) mixture on platinum in an aqueous electrolyte without added redox agents (80). Cathodic photocurrents with quantum efficiencies in the order of 10- were obtained with films consisting of a sufficient number of monolayers. The photocurrent was increased in acidic solutions. However, no appreciable photocurrent was observed with a single monolayer coated on platinum. The latter fact most probably results from minimal rectifying property of the metal surface and/or an efficient energy quenching of dye excited states by free electrons in... 

Deep levels interact with free carriers as either recombination centres or traps. Consequently, deep levels can significantly influence the photoelectric or electronic properties of a semiconductor. For example, in the active region of light emitting diodes deep levels can act as efficient non-radiative recombination centres and significantly limit the internal quantum efficiency. Other applications may utilise deep levels for the benefit of device performance. 

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