Semiconductor barrier

Santos TS, Lee JS, Migdal P, Lekshmi IC, Satpati B, Moodera JS (2007) Room temperature tunnel magnetoresistance and spin-polarized tunneling through an organic semiconductor barrier. Phys Rev Lett 98 016601... 

A sandwich comprising a semiconductor between two metallic electrodes presents the same effective barrier irrespective of the sense of an applied voltage. The situation is illustrated in Fig. 2.21. The resistance will be high at low voltages, because few electrons cross the barriers, but will be low once a voltage is reached which enables electrons to cross the metal-semiconductor barrier at a significant rate. The resulting characteristic is shown in Fig. 2.22 and is similar to that for two rectifiers back to back. 

Sze, S., Physics of semiconductor devices. New York, John Wiley Sons, 1981. Crowell, C. and Sze, S., Current transport in metal-semiconductor barrier,Solid State Electron, 1966,9,1035-48. 

Crowell, C. and Rideout, V., Normalized thermionic-field emission in metal-semiconductor barriers . Solid State Electron, 1969,12,89-105. 

The theoretical approach to band lineups outlined above, yields a metal/semiconductor barrier height of the form [53] ... 

Schliiter, M. 1978. Chemical trends in metal-semiconductor barrier heights. Phys Rev B 17 5044-5047. 

Some care must be exercised when using the reverse saturation current obtained from the semilogarithmic current voltage plot and equation 12 to determine the metal-semiconductor barrier height c()g. Card and Rhoderick have shown that if the interfacial oxide is sufficiently thick so that the electron tunnelling transmission coefficient is no longer unity then the reverse saturation current is reduced to a value equal to the product of the reverse saturation current when no interfacial layer is present and the transmission coefficient of the interfacial oxide> that is... 

Since T (6) is less than unity, the effective barrier height is higher than the barrier height when no interfacial oxide is present. Card and Rhoderick have attempted to quantify T (6) in terms of the thickness and work function of the interfacial oxide in gold n-type silicon MIS SBs. However, calculations based on their experimental data showed that for oxide thicknesses between 0.8 nm and 2.6 nm the work function properties did not necessarily resemble those of bulk silicon dioxide and made theoretical cal culation of T (6) impossible. Because of this, c > is best thought of as simply that value of metal-semiconductor barrier height which when used in conjunction with equations 11 and 12 provides an accurate prediction of the forward bias current voltage relationship. 

SOLAR CELL PARAMETERS AND DESIGN CONSIDERATIONS 3.1. Metal-Semiconductor Barrier Height... 

The previous model erases aU electrical fields and interfacial barriers in the mesostructure, which is viewed in effect as a homogeneous medium. However, in semiconductor mesostructures, filled with an HTM, one can also allow for the presence of an electrical field and semiconductor barrier at the internal interface ETM/HTM. The prevalence of one approach or the other, i.e., a macrohomogeneous model that only contemplates the Fermi level or the explicit presence of internal interface barriers, depends on doping densities, size of semiconductor particles or wires, and Debye length both in the semiconductor nanostructure and in the HTM [95-97]. 

Nowadays an important position belongs to the infrared detectors incorporating the mentioned wide-bandgap semiconductor barrier [368-370] (the BIRD detector —Barrier Infrared Detector). Maimon and Wicks proposed to use unipolar BIRDs —i.e., the built-in barrier layer blocks one carrier type, but allows free flow of the other type [371]. Such structures are for instance nBn. Ting et al. proposed the use of complementary barriers, one for electrons, another for holes, positioned at different depths [372]. Itsuno et al. analyzed NBvN and nBn detectors (where B stands for Barrier) [373, 374]. In their 2013 paper Martinyuk et al. quoted that besides Auger suppression the BIRD devices also suppress Shockley-Read-Hall g-r processes [375]. 

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