(1) We developed a noise measurement system.The success of the system is attributed to the current amplifier and the method of noise measurement designed by our group to improve the measurement accuracy.
(2) The nonradiative lifetime of the electrons and holes in the semiconductor can be measured with the photocurrent noise. We utilized this concept to confirm the Schockley Read Hall recombination theory with experiments and demonstrated the smallest lifetime the system could measure was about ~10 nanoseconds.
(3) The superlattice infrared photodetector was successfully designed and demonstrated. The associated detectivity is compatible with the conventional quantum well infrared photodetector. The primary advantage is low-power dissipation and low bias voltage . The detector can be utilized to sense the practical temperature of the remote object. The experiment demonstrates the remotely-sensing temperature range is 350~1000K.
(4) Stacking two different superlattices and inserting an appropriate blocking barrier, we successfully developed the four-color infrared photodetector with much better performance. The detector performance of independent of the operating temperature. The detected wavelength range can be switched by the bias polarity and the spectral response in one wavelength range can be tuned by the bias magnitude. The result is cited as a newsbreak in the June issue of Laser Focus World 2002.
(5) Understanding the physical mechanisms is helpful to the device design. It is found that the group velocity of the electrons in the miniband of the superlattice structure is a key factor to design the detector. This result is wholly different from the drift velocity of electrons used in the conventional quantum well infrared photodetector . It also renders a different design principle.
(6)The electronic beam system ELS7500 and ELS7000 can develop nano-scale-high-performance device. In optical circumstances, the system can make a device that reaches 10 nano-meter line width and minimize the device. We expect the device can be integrated into VLSI systems.