Yong Hoon Kang

Effect of the dot size distribution on quantum dot infrared photoresponse and temperature-dependent dark current

The fit allows us to find the standard deviation and the average activation energy for electrons in the dot distribution, which is consistent with the peak energy of the photocurrent spectrum measured in the middle infrared. On the contrary, the activation energy found from a conventional Arrhenius fit is well below the photocurrent peak energy.

A study on doping density in InAs/GaAs quantum dot infrared photodetector

We study the influence of doping density and the resulting optimum operation voltage on the performance of quantum dot infrared photodetectors (QDIPs). The optimum operation voltage, where detectivity becomes maximum, becomes smaller as the doping density increases. This is because the optimum dark current levels are similar regardless of the doping density. We confirmed experimentally that the optimum dark current level is ~5 mA (current density: ~A/cm2) for our samples. It is found that the higher doping density improves the performance in the range used in this experiment (5×1016–5×1017/cm3). The response to a normal incident light is confirmed and the possibility of high-temperature operation of QDIP is shown.

A simple Flash memory cell model for transient circuit simulation

A simple Flash memory cell model for circuit simulation is presented. The proposed model gives an excellent fitting of dc and transient data and does not require additional simulation time comparing with that of a MOSFET transistor. Effective control-gate voltage method and ideal current-mirror technique are introduced to calculate floating-gate voltage. These allow macro modeling of a Flash memory cell in a circuit simulator.

Quantum-well infrared phototransistor with pHEMT structure

A quantum-well infrared phototransistor with a pseudomorphic high-electron mobility transistor (pHEMT) structure is presented. The proposed phototransistor uses four periods of a GaAs/Al/sub 0.3/Ga/sub 0.7/As (50 /spl Aring//120 /spl Aring/) quantum-well absorption region, as well as an In/sub 0.15/Ga/sub 0.85/As quantum well conducting channel under the absorption layer. The phototransistor shows a large responsivity of 140 A/W around 6 /spl mu/m at 23 K (for a cutoff wavelength of 7.5 /spl mu/m). The relation between the photoconductive gain and the transconductance of the pHEMT structure is also investigated.

Study On Low Bias Avalanche Multiplication In Modulation Doped Quantum‐Dot Infrared Photodetectors

An avalanche gain mechanism of InAs/GaAs quantum dot infrared photodetector is presented. We observed a low voltage avalanche process from the modulation doped n‐i‐n quantum‐dot infrared photodetector. This is due to the remained electrons at modulation doped region.

Quantum Well Infrared Photodetector with pHEMT structure

This work was supported, in part, by KISTEP (under Nano-Structure Technology Projects and IMT2000 R&D donation support program) and the MOE BK21 program

Dark current study of quantum dot infrared photodetector

The distribution of bound state energies of self-assembled quantum dots in quantum dot infrared photodetector structure is addressed using its temperature-dependent dark currents. The temperature-dependent dark currents have been fitted by the modified Arrhenius equation, which includes the distribution of activation energies. The fitting allows us to find the standard deviation and the average activation energy. It is found that the peak of photocurrent spectra, which correspond to intersubband transition energy, is coincided with the average of the activation energies. This was never achieved with the conventional Arrhenius equation.