Koji Kusunoki

P‐143: Possibility of Reflective LC Display Using Oxide Semiconductor TFTs as Electronic Paper Display

We successfully prototyped a 3.4-inch QHD PDLCD panel integrally including data and scan drivers of oxide semiconductor TFTs and capable of displaying still images at 0.2 fps, which can be adopted to electronic paper displays. This panel can display both still images and moving images and reduce power consumption.

6.0-Inch Extended Graphics Array Reflective Liquid Crystal Display Using Oxide Semiconductor Thin Film Transistors for Electronic Paper Display

We focused on the off-state current (Ioff) of oxide semiconductor thin film transistors (TFT) (In–Ga–Zn-oxide TFTs), which is lower than that of amorphous silicon TFTs and successfully made a prototype of a 6.0-in. extended graphics array (XGA) reflective liquid crystal display (RLCD) panel integrally including a data selection demultiplexer and a scan driver and capable of displaying still images at 1/180 fps. When still images are displayed, the frame frequency can be set low. This means that the frequency of rewrites of image data is markedly reduced. This leads to the reduction in the power consumption of an LCD panel. Our panel can solve the problems of electronic paper displays: high drive voltage and difficulty of displaying moving images. Thus, our panel is suitable for electronic paper displays.

Transition from Excitonic Tunneling to Free Carrier Tunneling in GaAs/AlGaAs Double Quantum Wells

Nonresonant carrier tunneling has been studied as a function of temperature in GaAs/AlGaAs double quantum wells (DQWs). Time-resolved pump and probe reflectance measurements allow the direct observation of tunneling at any temperature between 15 K and room temperature. We found that for two DQWs with different barrier thicknesses, the tunneling time abruptly decreases above a critical temperature while it remains almost constant below the critical temperature. This critical temperature is shown to correspond to the exciton binding energy. Rate equation analysis explains this behavior as the thermalization of excitons into free electrons that have a faster tunneling time than excitons.

Thermally activated carrier transfer among CdTe∕ZnTe self-organized quantum dots

Carrier transfer among CdTe∕ZnTe self-organized quantum dots (QDs) was studied using time-resolved photoluminescence (PL) measurements. The authors have confirmed that carriers in the high energy ground states of small QDs transfer to the lower-energy ground states of larger QDs even at 10K. The energy dependence of PL decay time changes uniquely with increasing temperature. They have found that the change in the energy dependence of PL decay time can be explained by thermally activated carrier transfer.