在公共场合A Thesis Submitted in Partial Fulfillment of the Requirements
for the Degree of Master of Science
The effection of the width of the double-barrier parabolic quantum well on the magnetotunneling
Candidate : Yide Liu
新加坡留学生活费Major : Optics
Supervisor: Professor Ze Cheng
Huazhong University of Science & Technology
Wuhan 430074, P.R. China
May , 2008
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本人声明所呈交的学位论文是我个人在导师指导下进行的研究工作及取得的研究成果。尽我所知，除文
中已经标明引用的内容外，本论文不包含任何其他个人或集体已经发表或撰写过的研究成果。对本文的研究做出贡献的个人和集体，均已在文中以明确方式标明。本人完全意识到，本声明的法律结果由本人承担。
学位论文作者签名：刘易德
大快朵颐是什么意思
日期：2008 年5月14日
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学位论文作者签名：刘易德指导教师签名：成泽
日期：2008 年5月14日日期：2008 年 5 月14日
摘要核糖体
自江崎和朱兆祥提出超晶格概念以来，半导体超晶格和量子阱中的电子输运现象就成为国际热点之一。尤其是共振隧穿，人们可以沿平行于、垂直于或倾斜于半导体异质结生长方向施加磁场。同样在半导体生长技术的发展下，量子阱可以做成各种形状，诸如方型、抛物型、三角型等。
本文详尽研究了由1x x Al Ga As /GaAs 材料构成的双势垒抛物量子阱中电子在横向磁场中的隧穿问题，计算并模拟了对称结构和非对称结构关于阱宽对电子隧穿的传输系数的影响。横向磁场对电子隧穿过程的影响较为复杂，主要原因是由于电子横向动量守恒被破坏。我们采用转移矩阵理论计算了对称结构和非对称结构对于各种阱宽的传输系数。发现随着随着阱宽的增加，共振峰逐渐向低能方向移动。阱宽较小时，变化剧烈；阱宽较大时，变化缓慢。随着阱宽的增加，共振峰逐渐增多，共振峰由平缓逐渐变尖锐，共振峰之间的间距逐渐减小。对称结构较非对称结构共振峰更尖锐，更易产生共振隧穿现象。对于一定的阱宽，沿异质结生长方向施加的横向磁场致使共振峰向高能级移动，这是因为
磁场提高了有效势，进而提高了势阱中束缚能级即共振能量。但在不同的势阱中，磁场的影响不同，与阱宽的大小成正比，磁场对阱宽大的影响较阱宽小的大。
关键词：共振隧穿 抛物阱 共振峰 磁场
Abstract
The phenomenon of electric transport in the miconductor superlattice and quantum well become one of the hotspots in the international since the Tsu and Esaki put forward the concept of superlattice .Especially resonant tunneling ,the people can add magnetic field parallel,perpendicular or incline to the growth of the miconductor in heterostructures.With the development of the miconductor growth technology,the quantum well can be made into all kinds of shapes,such as square type, parabolic type or triangle type quantum well and so on.
In this paper,I studied the resonant tunneling of the electric in the double-barrier parabolic quantum well,it is made of 1x x Al Ga As /GaAs material,discusd the transmission of the electric in the configuration of the symmetry and asymmetry in the perpendicular magnetic field in detail.It's complexity for the electric transport in the perpendicular magnetic field,the mostly reason is the perpendicular momentum not conrvation about the electric.In this paper,I adopted the transfer mat
rix theory,calculated the transmission of the electric in the perpendicular magnetic field,I found that the resonant apexes moved to the low energy when the breadth of the quantum well incread,the bigger breadth of the well, the transmission of the electric change acute with the incidence energy,or el it change slowness.The resonant apexes manifold gradually with the breadth of well incread,which is from gently to acuity for the well incread.the distance between the two resonant apexes minished gradualy.Compare with the the symmetry and asymmetry configuration,the transmission resonant apexes is more acuity for the symmetry and the resonant is easyer to be realized.It is well known that the magnetic field can move the resonant apexes to higher energy for it enhanced the efficient potential,namely enhanced the bondage energy in the potential well,but for the different breadth of the potential well ,the influence of the magnetic field is diffenent,it depends on
片断教学
breadth of the well.The influence of the magnetic field in big breadth well is more notability than in the small .
Keywords: resonant tunneling parabolic well resonant apex magnetic field
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