Sri Purwiyanti

Photon-Induced Random Telegraph Signal Due to Potential Fluctuation of a Single Donor--Acceptor Pair in Nanoscale Si p--n Junctions

We study the photoresponse of Si nanoscale p–n and p–i–n diodes. As a result, we find a photon-sensitive multilevel random telegraph signal (RTS) in p–n diodes, but not in p–i–n diodes. From this fact and analysis of current jumps in the RTS, the multilevel RTS is ascribed to single photocarrier charging and discharging in a donor–acceptor pair in the depletion region. Thus, it is found that a donor–acceptor pair plays an important role in p–n junctions, while, according to our previous report, a single donor (acceptor) works as an electron (hole) trap in junctionless field-effect transistors.

Dopant-induced random telegraph signal in nanoscale lateral silicon pn diodes at low temperatures

We studied current-voltage characteristics of nanoscale pn diodes having the junction formed in a laterally patterned ultrathin silicon-on-insulator layer. At temperatures below 30 K, we observed random telegraph signal (RTS) in a range of forward bias. Since RTS is observed only for pn diodes, but not for pin diodes, one dopant among phosphorus donors or boron acceptors facing across the junction is likely responsible for potential changes affecting the current. Based also on potential measurements by low-temperature Kelvin probe force microscope, RTS is ascribed to trapping/detrapping of carriers by/from a single dopant near the farther edge of the depletion region.

Study of quantized-energy effects in Si nanoscale lateral pn junction diodes

In this work, we study SOI nanoscale pn junctions and find that transport characteristics are strongly affected by states of individual dopants and by quantized energy states. For pn diodes with lower doping concentration, we find that individual dopant atoms work as electron traps, inducing RTS in the diode current. On the other hand, for highly-doped pn diodes, quantization effects play critical roles in transport characteristics for both forward and reverse bias regimes.

Impact of Dopant Induced States on Interband Tunneling in Nanoscale pn Junctions

We report on an interband tunneling nanoscale Si pn junction with high doping concentration of ~5.0×10 cm. We find that transport characteristics show step-like structure, indicating that interband tunneling is strongly influenced by dopant-induced states of the depletion region. Also, we find a current peak observed in reverse bias condition at low temperatures, indicating that the dopant states can directly contribute to interband tunneling current. This is different from pn junctions with low doping concentration of ~1.0×10 cm, in which individual dopant atoms work as electron traps.

A simulation of the applied bias effect of tunnelling probability in quadruple barrier Si/SiO 2 system

Recently, multiple quantum wells structure are often used in the laser and diode applications in order to increase their efficiency. In this structure, electron tunnelling phenomena from a quantum well to another well play a key role in electronic transport itself. Tunnelling is a quantum mechanical phenomenon where an electron is commonly represented by its wavefunction. This paper presents a numerical simulation of electron tunnelling probability on three quantum wells (quadruple barrier) Si/SiO2 system focusing the applied bias effect on the tunnelling probability. The tunneling probability is calculated by solving the Schrodingers equations through potential barrier using transfer matrix method. The simulation results show the mini-band formation due to the appearance of discrete energy group. We also found that the applied bias on this structure causes the changes in tunnelling probability and discrete energy gap. Therefore, the control of voltage bias and device structure is required in order to obtain expected characteristic of multiple quantum well structure.

Simulation of mini-band formation in triple si quantum wells based resonant tunneling diode

In this work, we investigate the formation of mini-band energy in triple Si quantum wells-based resonance tunnelling diode focusing on the effect of applied bias on the band. The formation of mini-bands is obtained from the calculation of electron tunnelling probability through the wells. The calculation is done based on transfer matrix method. The simulation results show the mini-band formation due to the appearance of discrete energy group. The changes of applied bias, quantum well width and barrier thickness causes the change of the mini-band width. These results indicate that the device structure and applied bias condition play a key role on the formation of mini-band energy in the quantum wells.