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物理論壇85期-博士生中期考評

(一)2-D PIEZOELECTRIC SEMICONDUCTOR MATERIALS WITH COUPLING OF PIEZOELECTRIC AND SEMICONDUCTOR PROPERTIES FOR OPTOELECTRONIC DEVICES

REASEARCH CONTENT: Two dimensional (2D) piezoelectric semiconductors are 2D materials which have both piezoelectric and semiconductor properties. These materials have a non-centrosymmetric structure, which exhibits high potential in nanoscale, electromechanical systems, and optoelectronic devices. There is a growing interest for these 2D piezoelectric semiconductor materials in optoelectronics devices, energy harvesting, and electronics Piezoelectric effect produces polarization charges under mechanical deformation in materials lacking inversion symmetry/center of symmetry or with polarization domains. The effect of mechanically-induced polarization on electronic and optoelectronic processes of charge carriers in piezoelectric materials has therefore been long overlooked. The coupling between piezoelectric polarization, semiconductor and it properties has resulted in both novel fundamental phenomenon and unprecedented device applications, paving way for an increasing research interests in the emerging field of piezotronics and piezo-phototronics. The core content of this work involve the coupling between piezoelectric polarization, 2-D semiconductor and it properties for optoelectronic device application.  The fundamental principle of piezotronics and piezo-phototronics lies in the fact that strain-induced polarization charges introduce at interface can effectively regulate the local band structure and enhance the charge carrier transport across local junctions/contacts by exhibiting substantial influence on the concentration or distribution of free carriers and interfacial electronic charged states in the applied devices. By successfully applying the piezotronic and piezo-phototronic effects in optoelectronic devices, we have shown how these two effects can be utilized in various practical applications as effective way of modifying the physical properties of charge carriers in piezoelectric semiconductors.

報告人簡介:Gyan Michael,(留學生博士研究生。

博士生導師:張巖 教授

報告時間:11219:00 11:00

報告地點:物理樓204會議室

主持人:張巖教授

(二)化電場調控低維壓電半導體自旋特性的研究

Spin Properties of Low-dimensional Piezoelectric Semiconductor Modulated by Polarization Electric Field

內容簡介:我們研究了異質結材料界面處二維電子氣的量子行為,探討了外部應力作用下電子量子狀態的轉變過程,給出了界面電子氣的濃度、能級以及電子密度分布。結果明力誘導的極化場能夠誘發量子態的產生,使得界面電子濃度發生較大改變。此外,顯著的量子能級分布為內躍遷提供了可能,但由于極化場嚴重破壞了界面的對稱性,導致躍遷強度較弱,難以得到應用。為了解決這種困難,我們關注點投入在量子阱帶內躍遷。利用強的壓電場來抵消材料固有的極化場,降低了由于場引起的不對稱性,有效地增強了躍遷強度。研究方法上,我們改進了薛定諤方程求解方法,利用自洽耦合八帶kp哈密頓與泊松方程,計算了量子阱內的狀態分布,能夠更好地與實驗結果進行對比。該報告首次研究了壓電電子學效應在躍遷上的應用,為遠紅外及太赫茲光電器件應用提供了理論指導。

報告人簡介:胡功偉,博士研究生,主要從事功能納米結構及其物理。


博士生導師:張巖 教授


報告時間:11219:00 11:00


報告地點:物理樓204會議室


主持人張巖教授

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