黃錦勝，林少光，林凱燕，陳國貴

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外加磁場下類氫施主雜質(zhì)量子點中的激子

黃錦勝，林少光，林凱燕，陳國貴

（揭陽職業(yè)技術(shù)學(xué)院 師范教育系，廣東 揭陽 522051）

利用精確對角化方法計算了外加磁場下類氫施主雜質(zhì)量子點中的激子的束縛能，發(fā)現(xiàn)系統(tǒng)的束縛能隨著量子點的束縛勢的增大而減小，隨著外加磁場的增大而減小.

類氫施主雜質(zhì)；量子點；磁場；束縛能

1 理論推導(dǎo)

引入二維諧振子波函數(shù)乘積基：

2 計算結(jié)果和討論

本文著重考查束縛態(tài)的存在會受到哪些條件的影響. 參照文獻(xiàn)[17]束縛能表示為

其中，是雜質(zhì)系統(tǒng)激子的本征能量，是空穴在拋物勢量子點中的最低能量，其不受庫侖勢作用，是雜質(zhì)束縛著電子的基態(tài)能. 從式(6)可以看出，束縛能就是把空穴從雜質(zhì)系統(tǒng)內(nèi)激子的束縛態(tài)中分離出來，成為在量子點中具有基態(tài)能為的單粒子態(tài)所需的最低能量. 當(dāng)時，激子在雜質(zhì)系統(tǒng)存在束縛態(tài).

圖2 施主雜質(zhì)系統(tǒng)中激子基態(tài)能和電子基態(tài)能隨束縛勢大小的變化關(guān)系

圖3 施主雜質(zhì)系統(tǒng)中激子基態(tài)(L=0)和第一激發(fā)態(tài)(L=1)束縛能隨外加磁場大小的變化關(guān)系

圖4 施主雜質(zhì)系統(tǒng)中激子基態(tài)束縛能隨電子空穴質(zhì)量比大小的變化關(guān)系

3 結(jié)論

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[8] GOMEZ S S, ROMERO R H. Binding energy of an off-center shallow donor D- in a spherical quantum dot [J]. physica E,2010, 42(5): 1563-1566.

[9] ZENG Zaiping, GAROUFALIS C S, BASKOUTAS S, et al. Stark effect of donor binding energy in a self-assembled GaAs quantum dot subjected to a tilted electric field [J]. Phys Lett A, 2012, 376(42-43): 2712-2716.

[10] XIE Wenfang, GU Juan. Exciton bound to a neutral donor in parabolic quantum dots [J]. Phys Lett A, 2003, 312(5-6): 385-390.

[11] BASKOUTAS S, SCHOMMERS W, TERZIS A F, et al. Stability of an exciton bound to an ionized donor in quantum dots [J]. Phy Lett A, 2003, 308(2-3): 219-225.

[12] SKETTRUP T, SUFFCZYNSKI M, GORZKOWSKI W. Properties of excitons bound to ionized donors [J]. Phys Rev B, 1971, 4(2): 512-517.

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[14] RUAN Wenying, CHANG Yia-chung, Stability of ion-bound excitons in two dimensions [J]. Phys Rev B, 2002, 66(11): 115-314.

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[17] XIE Wenfang, GU Juan. Binding energies of an exciton bound to a charged impurity in quantum dots [J]. Physica B, 2003, 337: 58-63.

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[責(zé)任編輯：韋 韜]

Exciton of a Hydrogenic Donor Quantum Dot in a Magnetic Fields

HUANGJin-sheng, LINShao-guang, LINKai-yan, CHENGuo-gui

(Department of Normal-education, Jieyang Vocational Technology College, Jieyang 522051, China)

An investigation of binding energy of a hydrogenic donor in a parabolic quantum dot with exciton under magnetic field is calculated by using the matrix diagonalization method. The results indicate that the binding energy decreases with increasing confinement strength and also decreases with increasing the magnetic field strength.

Hydrogenic donor; Quantum dot; Magnetic field; Binding energy

1006-7302（2013）01-0050-05

O474

A

2012-10-09

揭陽職業(yè)技術(shù)學(xué)院重點資助項目（JYCKZ1102）

黃錦勝（1980—）, 男，廣東梅州人, 講師，碩士，主要從事低維半導(dǎo)體材料光學(xué)性質(zhì)研究.