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Observation of strong anisotropic forbidden transitions in (001) InGaAs/GaAs single-quantum well by reflectance-difference spectroscopy and its behavior under uniaxial strain.

Yu JL, Chen YH, Tang CG, Jiang C, Ye XL - Nanoscale Res Lett (2011)

Bottom Line: The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K.Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition.It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P,O, Box 912, Beijing 100083, People's Republic of China. yhchen@semi.ac.cn.

ABSTRACT
The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K. Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition. It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect. The effect of uniaxial strain on in-plane optical anisotropy (IPOA) is also investigated. The IPOA of the forbidden transition changes little with strain, while that of the allowed transition shows a linear dependence on strain.PACS 78.66.Fd, 78.20.Bh, 78.20.Fm.

No MeSH data available.


Related in: MedlinePlus

Real part of RD spectra and ΔR/R spectra of In0.2Ga0.8As/GaAs single-quantum well with nominal well width 3, 5, and 7 nm, respectively. The spectra are measured at 80 K. The vertical lines indicate the energy positions of the transitions 1e1hh (solid) and 1e1lh (dotted). And the vertical arrows indicate the positions of 1e2hh (upward arrows), leh* (downward arrows), and 2e2hh (downward arrows). Here h* represents continuous hole states.
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Figure 2: Real part of RD spectra and ΔR/R spectra of In0.2Ga0.8As/GaAs single-quantum well with nominal well width 3, 5, and 7 nm, respectively. The spectra are measured at 80 K. The vertical lines indicate the energy positions of the transitions 1e1hh (solid) and 1e1lh (dotted). And the vertical arrows indicate the positions of 1e2hh (upward arrows), leh* (downward arrows), and 2e2hh (downward arrows). Here h* represents continuous hole states.

Mentions: Figure 2 shows the real part of the RD and ΔR/R spectra of the three samples obtained at 80 K. In the ΔR/R spectra, we can observe the transitions of 1e1hh (the first conduction to the first valence subband of heavy hole), 1e1lh and 2e2hh, and what's more, the intensity of the transition 1e1hh is much larger than that of the 1e1lh. However, in the RD spectra, besides the allowed transitions 1e1hh, 1e1lh, 2e2hh and 1eh*, we can also observe the forbidden transition 1e2hh. Here h* represents continuous hole states. The energy positions of the transitions 1e1hh (1e1lh) are marked by solid (dotted) lines. And the positions of 1e2hh, 1eh* and 2e2hh are indicated by upward, green downward and black downward arrows, respectively. The transitions 1e1hh and 1e1lh show peak-like lineshape (negative or positive), while the forbidden transitions 1e2hh of the samples with well width 5 and 7 nm present a smoothed-step-like lineshape. This phenomenon may be attributed to the coupling of heavy and light holes when the in-plane wave vector is nonzero [1]. For the sample with well width 3 nm, it is difficult to clearly distinguish the corresponding energy positions of the transitions 1e2hh, 1e1lh and leh*, because they are too close to each other. Even so, we can still observe that, the intensity of the IPOA of 1e1lh increases obviously compared to that of 1e1hh. Surprisingly, the forbidden transition 1e2hh are comparable to the allowed transition in RD spectra, while it almost cannot be observed in ΔR/R spectra.


Observation of strong anisotropic forbidden transitions in (001) InGaAs/GaAs single-quantum well by reflectance-difference spectroscopy and its behavior under uniaxial strain.

Yu JL, Chen YH, Tang CG, Jiang C, Ye XL - Nanoscale Res Lett (2011)

Real part of RD spectra and ΔR/R spectra of In0.2Ga0.8As/GaAs single-quantum well with nominal well width 3, 5, and 7 nm, respectively. The spectra are measured at 80 K. The vertical lines indicate the energy positions of the transitions 1e1hh (solid) and 1e1lh (dotted). And the vertical arrows indicate the positions of 1e2hh (upward arrows), leh* (downward arrows), and 2e2hh (downward arrows). Here h* represents continuous hole states.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211267&req=5

Figure 2: Real part of RD spectra and ΔR/R spectra of In0.2Ga0.8As/GaAs single-quantum well with nominal well width 3, 5, and 7 nm, respectively. The spectra are measured at 80 K. The vertical lines indicate the energy positions of the transitions 1e1hh (solid) and 1e1lh (dotted). And the vertical arrows indicate the positions of 1e2hh (upward arrows), leh* (downward arrows), and 2e2hh (downward arrows). Here h* represents continuous hole states.
Mentions: Figure 2 shows the real part of the RD and ΔR/R spectra of the three samples obtained at 80 K. In the ΔR/R spectra, we can observe the transitions of 1e1hh (the first conduction to the first valence subband of heavy hole), 1e1lh and 2e2hh, and what's more, the intensity of the transition 1e1hh is much larger than that of the 1e1lh. However, in the RD spectra, besides the allowed transitions 1e1hh, 1e1lh, 2e2hh and 1eh*, we can also observe the forbidden transition 1e2hh. Here h* represents continuous hole states. The energy positions of the transitions 1e1hh (1e1lh) are marked by solid (dotted) lines. And the positions of 1e2hh, 1eh* and 2e2hh are indicated by upward, green downward and black downward arrows, respectively. The transitions 1e1hh and 1e1lh show peak-like lineshape (negative or positive), while the forbidden transitions 1e2hh of the samples with well width 5 and 7 nm present a smoothed-step-like lineshape. This phenomenon may be attributed to the coupling of heavy and light holes when the in-plane wave vector is nonzero [1]. For the sample with well width 3 nm, it is difficult to clearly distinguish the corresponding energy positions of the transitions 1e2hh, 1e1lh and leh*, because they are too close to each other. Even so, we can still observe that, the intensity of the IPOA of 1e1lh increases obviously compared to that of 1e1hh. Surprisingly, the forbidden transition 1e2hh are comparable to the allowed transition in RD spectra, while it almost cannot be observed in ΔR/R spectra.

Bottom Line: The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K.Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition.It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P,O, Box 912, Beijing 100083, People's Republic of China. yhchen@semi.ac.cn.

ABSTRACT
The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K. Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition. It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect. The effect of uniaxial strain on in-plane optical anisotropy (IPOA) is also investigated. The IPOA of the forbidden transition changes little with strain, while that of the allowed transition shows a linear dependence on strain.PACS 78.66.Fd, 78.20.Bh, 78.20.Fm.

No MeSH data available.


Related in: MedlinePlus