摘要
采用自洽计算方法对BST/AlGaN/GaN铁电/半导体异质结构中二维电子气进行研究,通过计入铁电极化随电场变化的非线性关系,模拟了对该异质结构进行"极化/退极化"(加负/正偏压)后,由铁电极化偶极子翻转导致的二维电子气浓度的变化情况。当对BST/AlGaN/GaN异质结构进行"极化"后,BST极化偶极子部分反转使得BST/AlGaN界面处感生高浓度负极化电荷,对二维电子气产生耗尽作用,而由于极化钉扎作用,此时BST的平均极化方向仍与Al-GaN中极化方向相同。当对异质结构进行"退极化"后,BST极化偶极子排列与AlGaN中极化方向相同,二维电子气浓度增加。随AlGaN势垒层厚度减小,BST极化对二维电子气的调制作用增强。另外,通过C-V测量方法对BST/AlGaN/GaN样品进行小范围电压扫描发现C-V曲线呈逆时针滞回方向,证实了铁电体极化对二维电子气的调制作用。
The two-dimensional electron-gas(2DEG)in BST/AlGaN/GaN ferroelectric/semiconductor heterostructure was theoretically investigated by using a self-consistent method.By incorporating the switchable polar nature of ferroelectric into the calculation,the control effect of the ferroelectric polarization on the 2DEG density was simulated after 'poling/depoling' operation on the heterostructure.It is clarified that the direction of the average polarization of BST is parallel to that of the AlGaN barrier after poling operation.Owing to the partially reversed dipole,the 2DEG density was depleted because of the increased negative polarization charge at the BST/AlGaN interface.While the depoling operation makes the dipoles of BST fully aligned and the 2DEG density is restored.Further study shows that the control effect is enhanced with decreasing the thickness of the AlGaN barrier.The C-V measurement was performed under different conditions.The small region scan results in a counterclockwise hysteresis loop,which confirms the modulation effect of ferroelectric polarization on the 2DEG in the channel.
出处
《半导体技术》
CAS
CSCD
北大核心
2008年第S1期83-86,共4页
Semiconductor Technology
基金
国家"973"重点基础研究项目(61363Z03.2)
关键词
铁电/半导体异质结构
极化调制
二维电子气
ferroelectric/semiconductor heterostructure
polarization modulation
two-dimensional electron-gas(2DEG)
