Theoretical nnaalysis on control of polarization field in GaN-based quantum dot structures and improvement of lasing performance

GaN基量子点结构偏振场控制及激光性能提升的理论分析

• 批准号: 14550003
• 负责人: SAITO Toshio
• 金额: $ 1.34万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550003/
• 关键词: GaN; quantum dot; spontaneous polarization; piezoelectric polarization; strain distribution; electronic structures; semiconductor laser; oscillation performance; 半導体レーザー

We have calculated electronic states of GaN quantum dots (QDs) in AIN using a polarization-potential-dependent sp^3 tight-binding method. We used a Keating-type Valence-Force-Field method for the strain distribution, and a finite-difference method for potential and electric field induced by polarization. The spontaneous and piezoelectric components of polarization are included in the present calculation. We examined a truncated-pyramidal GAN QDs with the base diameter 10.14 nm and the height 2.07nm. This dot size corresponds to that grown in our experiments. It is found that the strong electric field (max.7.14MV/cm) is induced in the QDs due to the polarization. The ground transition energy is calculated to be 3.653 eV which lies in the photon energy rage of the photoluminescence. Owing to the strong electric field, the electron wave function is pushed up toward the top, and the hole wave function is pushed down toward the bottom of the QD. The overlap between the electron and hole wave functions is decreased, and thereby the electron-hole recombination rate is reduced. (the squared overlap is 7.97x10^<-2>.) we developed programs of a l-band effective-mass model and a 8-band k・p model in order to calculate electronic states of QDs with larger sizes. Using these programs, we calculated electronic states in vertically stacked InAs QDs. Here the elastic continuum model is used for the strain distribution. We found a weak coupling between the electronic states in the stacked QDs with the dot spacing 6nm. The programs can be used for calculating electronic states in stacked GaN QDs.

利用极化势相关的sp^3紧束缚方法计算了AlN中GaN量子点的电子态。应变分布采用Keating型的价力场方法，极化引起的电势和电场采用有限差分法。计算中考虑了自发极化和压电极化。我们制备了一个底部直径为10.14 nm、高度为2.07 nm的截棱锥形量子点。这个点的大小对应于我们实验中生长的点。结果表明，由于量子点的极化作用，量子点内部产生了很强的电场（最大值为7.14MV/cm）。计算出基态跃迁能为3.653eV，处于光致发光的光子能量范围内。由于强电场，电子波函数被推向顶部，空穴波函数被推向底部。电子和空穴波函数之间的重叠减少，从而电子-空穴复合率降低。(the平方重叠为7.97x10^<-2>）。我们开发了l带有效质量模型和8带k·p模型程序来计算更大尺寸的量子点的电子态。使用这些程序，我们计算了垂直堆叠的InAs量子点的电子态。在这里，弹性连续体模型用于应变分布。在量子点间距为6 nm的量子点中，发现了电子态之间的弱耦合。该程序可用于计算GaN量子点的电子态。

项目成果

T.Saito: "Atomistic Calculation of Electronic States in III-V Nitride Quantum Dots"Proc.of 3rd Int.Conf.on Numerical Simulation of Semiconductor Optoelectronic Devices. IEEE03EX726. 1-4 (2003)

T.Saito：“III-V 族氮化物量子点中电子态的原子计算”Proc.of 第三届半导体光电器件数值模拟国际会议。

T.Kakitsuka: "Numerical analysis of transition energy shift in InAs/GaAs quantum dots induced by strain-reducing layers"Physica Status Solidi (C). (in press). (2003)

T.Kakitsuka：“应变减少层引起的 InAs/GaAs 量子点中过渡能量转移的数值分析”Physica Status Solidi (C)。

T.Saito: "Electronic structure of piezoelectric In_<0.2>Ga_<0.8>N quantum dots in GaN calculated using a tight-binding method"Physica E. 15. 169-181 (2002)

T.Saito：“使用紧束缚方法计算的 GaN 中压电 In_<0.2>Ga_<0.8>N 量子点的电子结构”Physica E. 15. 169-181 (2002)

T.Saito et al.: "Polarization Field and Electronic States of GaN Pyramidal Quantum Dots in AIN"Physica Status Solidi(C). 0. 1169-1172 (2003)

T.Saito 等人：“AIN 中 GaN 金字塔量子点的极化场和电子态”物理状态固体 (C)。

T.Saito: "Quantum-confined Stark effect in InGaN pyramidal dots induced by the piezoelectric field"Compound Semiconductors 2001 (Proc.of the 28^<th> Int.Symp.on Compound Semiconductors). Inst.Phys.Conf.Ser.No.170. 555-560 (2002)

T.Saito：“由压电场引起的 InGaN 金字塔点中的量子限制斯塔克效应”Compound Semiconductors 2001（Proc.of the 28^<th> Int.Symp.oncompound Semiconductors）。