Electron mobility enhancement in nanoscale silicon-on-insulator diffusion layers with high doping concentration of greater than 1 × 1018 cm−3 and silicon-on-insulator thickness of less than 10 nm

Abstract

Articles you may be interested inMobility enhancement effect in heavily doped junctionless nanowire silicon-on-insulator metal-oxidesemiconductor field-effect transistors Electron mobility in nanoscale silicon-on-insulator (SOI) layers with a doping concentration ranging from 2 Â 10 17 cm À3 to 1 Â 10 19 cm À3 is thoroughly studied. We observe that electron mobility in highly doped nanoscale extremely thin SOI (ETSOI) layers with thicknesses ranging from 5 to 11 nm is greater than electron mobility in bulk Si with the same doping concentration. Since no dopant ion exists in the oxides above and below ETSOI, the absence of ions close to the ETSOI layers effectively reduces the number of Coulomb centers that scatter carriers in the ETSOI layers. We show that the ratio of SOI thickness to the average distance between donor ions is critically important to understand the mobility enhancement in nanoscale ETSOI. It is demonstrated that mobility enhancement can be universally described as a function of the ratio described above. The findings of our study are indispensable in designing aggressively scaled SOI metal-oxidesemiconductor field-effect transistors.

Deionization of Dopants in Silicon Nanofilms Even with Donor Concentration of Greater than 1019 cm–3

“…As a result, the metal–insulator transition is suppressed in nanoscale SOI FETs. As discussed in our previous work, reduction of overall potential fluctuation due to effectively less ionized impurities around carriers in nanoscale SOI films causes the mobility enhancement in heavily doped SOI FETs Figure c shows sheet electron concentration dependences of electron mobility in SOI FETs.…”

“…By applying the localoxidation-of-Si process, the channel region was more aggressively scaled than the source/drain regions. The detail of the process flow, including the timing of ion implantations, can be found in ref 26. The SOI channels were finally thinned to approximately 10 nm scales.…”

“…As discussed in our previous work, reduction of overall potential fluctuation due to effectively less ionized impurities around carriers in nanoscale SOI films causes the mobility enhancement in heavily doped SOI FETs. 26 Figure 4c shows sheet electron concentration dependences of electron mobility in SOI FETs. The mobility at the flat-band condition in SOI FETs is compared with mobility in bulk Si.…”

Low-temperature synthesis of indium tin oxide nanowires as the transparent electrodes for organic light emitting devices

“…In fact, such an enhanced mobility at the nanoscale has been recently detected in nanoscale silicon-on-insulator (SOI) [21]. The reason for such an enhancement is the figure 4(a), the mobility of a conducting electron in the ITO film is affected by both long-and short-range interactions with the surrounding lattice, both from the electron clouds and atoms with positive ionic cores.…”

Numerical analysis of band tails in nanowires and their effects on the performance of tunneling field-effect transistors

“…[7][8][9][10][11][12] Exponential decay is defined for bulk semiconductors. In nanostructured semiconductors, the situations around the dopants which cause the band tails are different from bulk semiconductors; the number of neighbor dopants is reduced 13,14) and potentials induced by dopants are greatly affected by surrounding dielectrics because of the large surface-to-volume ratio of nanostructures. [14][15][16][17][18][19] Thus, band tails in nanostructured semiconductors should also be changed from those in bulk semiconductors.…”