zhuohui chen - Academia.edu (original) (raw)
Related Authors
Graduate Center of the City University of New York
Uploads
Papers by zhuohui chen
Proceedings of Symposium on Ultrasonic Electronics
Analytical Sciences, 1992
Purely concentration-gradient driven liquid-liquid interface laser beam deflection detection was ... more Purely concentration-gradient driven liquid-liquid interface laser beam deflection detection was studied theoretically and used experimentally to monitor the kinetics of diffusion between water and sugar as a simple model system. The combination of data from both sides of the interface was used to determine the initial position of the interface plane. The developed one-dimensional model of the dependence of the laser beam deflection on the diffusion parameters was found to be in good agreement with the experimental data, especially at early interdiffusion times. The model was thus able to yield the values for the diffusion coefficient DS of sugar in water, and for the refractive index gradient an/3C.
The Journal of the Acoustical Society of America, 1993
Review of Scientific Instruments, 1992
The application of the rate-window concept, familiar from deep level transient spectroscopy, to t... more The application of the rate-window concept, familiar from deep level transient spectroscopy, to thermomodulation and photomodulation problems via lock-in detection has been investigated. Theoretical analysis of the newly adapted technique to these problems is presented and experimental photopyroelectric and photomodulated optical reflectance results are discussed. The utilization of the lock-in analyzer as a signal transient filtering system and as a dual-gate boxcar integrator equivalent with transient thermal wave signals is examined. Optimal instrumental conditions for use with thermal and electron-hole plasma analysis methodologies are presented, and experimental results with aluminum foil, crystalline and ion-implanted Si illustrate the potential of this measurement methodology for nondestructive thermal and electronic spectrometric evaluation of condensed phases and electronic materials.
Applied Physics Letters, 1991
To separate the majority and minority carriers in the deep level transient spectroscopy (DLTS), t... more To separate the majority and minority carriers in the deep level transient spectroscopy (DLTS), the transient is usually measured in the dark. However, under some circumstances, the transient measurement should be performed under illumination. In these cases, the effects introduced by the illumination become a concern. In this letter, effects of secondary laser illumination on samples of hydrogenated amorphous silicon (a-Si:H) during the transient measurement in optical and electrical DLTS are reported. The experimental results show that background illumination decreases the time constant of the transient but it is unlikely to create new gap states during the short time period. Deep level transient spectroscopy',* (DLTS) is a useful tool in determining the thermal emission properties of deep levels of impurities and defects in semiconductors. The energy levels and free-carrier-capture cross sections of these deep level defects are obtained by measuring the transients of electrical parameters, such as junction
A new noncontact technique for the determination of excess carrier lifetimes in semiconductors is... more A new noncontact technique for the determination of excess carrier lifetimes in semiconductors is presented. The technique employs a square laser pulse (hv > Eg) and measures the infrared photothermal radiometric response of the sample. By applying the photothermal rate-window concept, the excess photoexcited carrier bulk lifetime was measured with optimal signal-to-noise (S/N) ratio and simple, unambiguous interpretation from the maximum position of the rate-window signal. The technique has been applied to Au-, Fe-, and Cr-doped Czochralski silicon crystals. The experimental results from boxcar and lock-in rate-window methods were found to agree very well. The results are further mostly in agreement with those from the noncontact laser/microwave detection method.
physica status solidi (a)
Proceedings of Symposium on Ultrasonic Electronics
Analytical Sciences, 1992
Purely concentration-gradient driven liquid-liquid interface laser beam deflection detection was ... more Purely concentration-gradient driven liquid-liquid interface laser beam deflection detection was studied theoretically and used experimentally to monitor the kinetics of diffusion between water and sugar as a simple model system. The combination of data from both sides of the interface was used to determine the initial position of the interface plane. The developed one-dimensional model of the dependence of the laser beam deflection on the diffusion parameters was found to be in good agreement with the experimental data, especially at early interdiffusion times. The model was thus able to yield the values for the diffusion coefficient DS of sugar in water, and for the refractive index gradient an/3C.
The Journal of the Acoustical Society of America, 1993
Review of Scientific Instruments, 1992
The application of the rate-window concept, familiar from deep level transient spectroscopy, to t... more The application of the rate-window concept, familiar from deep level transient spectroscopy, to thermomodulation and photomodulation problems via lock-in detection has been investigated. Theoretical analysis of the newly adapted technique to these problems is presented and experimental photopyroelectric and photomodulated optical reflectance results are discussed. The utilization of the lock-in analyzer as a signal transient filtering system and as a dual-gate boxcar integrator equivalent with transient thermal wave signals is examined. Optimal instrumental conditions for use with thermal and electron-hole plasma analysis methodologies are presented, and experimental results with aluminum foil, crystalline and ion-implanted Si illustrate the potential of this measurement methodology for nondestructive thermal and electronic spectrometric evaluation of condensed phases and electronic materials.
Applied Physics Letters, 1991
To separate the majority and minority carriers in the deep level transient spectroscopy (DLTS), t... more To separate the majority and minority carriers in the deep level transient spectroscopy (DLTS), the transient is usually measured in the dark. However, under some circumstances, the transient measurement should be performed under illumination. In these cases, the effects introduced by the illumination become a concern. In this letter, effects of secondary laser illumination on samples of hydrogenated amorphous silicon (a-Si:H) during the transient measurement in optical and electrical DLTS are reported. The experimental results show that background illumination decreases the time constant of the transient but it is unlikely to create new gap states during the short time period. Deep level transient spectroscopy',* (DLTS) is a useful tool in determining the thermal emission properties of deep levels of impurities and defects in semiconductors. The energy levels and free-carrier-capture cross sections of these deep level defects are obtained by measuring the transients of electrical parameters, such as junction
A new noncontact technique for the determination of excess carrier lifetimes in semiconductors is... more A new noncontact technique for the determination of excess carrier lifetimes in semiconductors is presented. The technique employs a square laser pulse (hv > Eg) and measures the infrared photothermal radiometric response of the sample. By applying the photothermal rate-window concept, the excess photoexcited carrier bulk lifetime was measured with optimal signal-to-noise (S/N) ratio and simple, unambiguous interpretation from the maximum position of the rate-window signal. The technique has been applied to Au-, Fe-, and Cr-doped Czochralski silicon crystals. The experimental results from boxcar and lock-in rate-window methods were found to agree very well. The results are further mostly in agreement with those from the noncontact laser/microwave detection method.
physica status solidi (a)