Enhanced terahertz ISBT in GaAsBi/AlGaAs quantum well: impact of doping modulation

Figures & data

Table 1. Physical properties of SQW and BL used in the work. ${\mathrm{m}}_0$ is the mass of an electron and ${\mathrm{\epsilon }}_0$ is the vacuum permittivity.

Layer	$\mathit{\text{Eg}}\mathit{ }(\mathit{\text{eV}})$	Ref.	${\mathbf{\epsilon }/\mathbf{\epsilon }}_0$	Ref.	${\mathbf{m}}_{\mathbf{e} }^{\mathbf{*}}$/${\mathit{m}}_0$	Ref.
GaAs0.95Bi0.05 SQW	$1.007$	Usman, Broderick, Lindsay, and O’Reilly (2011), Pač̌ebutas, Bertulis, Aleksejenko, and Krotkus (2009)	$9.500$ $\left(\frac{{\mathrm{\epsilon } }_{\mathit{\text{QW}}}}{{\mathrm{\epsilon }}_0}\right)$	Yu, Li, Zhao, Li, and Yang (2012)	$0.0624$ $\left(\frac{{{\mathrm{m}}_{\text{e}}^{\mathrm{*}}}_{\mathit{\text{QW}}}}{m_0}\right)$	Maspero, Sweeney, and Florescu (2016), Zayan, Stevens, and Vandervelde (2016)
Al0.2Ga0.8 As BL	$1.673$	Vurgaftman, Meyer, and Ram-Mohan (2001), Adachi (1985)	$12.556$ $\left(\frac{{\mathrm{\epsilon } }_{\mathit{\text{BL}}}}{{\mathrm{\epsilon }}_0}\right)$	Adachi (1985)	$0.0796$ $\left(\frac{{{\mathrm{m}}_{\text{e}}^{\mathrm{*}}}_{\mathit{\text{BL}}}}{m_0}\right)$	NSM Archive - Physical Properties of Semiconductors (2024)

Figure 1. (a) Cross section of the GaAsBi/AlGaAs SQW structure under investigation. (b) Schematic band diagram of modulation-doped quantum well structure GaAs_1-yBi_y separated by an Al_xGa_1−xAs as barrier layer (BL).

Table 2. Summary of the used abbreviations.

Abbreviation	Definitions
${\mathrm{L}}_{\mathrm{\text{buf}}}$	GaAs buffer thickness
${\mathrm{L}}_{\mathrm{\text{cap}}}$	GaAs cap layer thickness
${\mathrm{L}}_{\mathrm{b}1}$ and ${\mathrm{L}}_{\mathrm{b}2}$	AlGaAs barrier layer (BL) thicknesses
${\mathrm{L}}_{\mathrm{\text{QW}}}$	GaAsBi QW width
${\Delta \mathrm{E}}_{\mathrm{c}}^{\mathrm{\text{int}}1}$	Conduction Band Offset between GaAs and AlGaAs layers
${\Delta \mathrm{E}}_{\mathrm{c}}^{\mathrm{\text{int}}2}$	Conduction Band Offset between AlGaAs and GaAsBi layers

Figure 2. The conduction band profiles for the studied structures A (a), B (b), and (c) along the $z$- direction. The left contact on the CB was set to zero energy arbitrarily.

Figure 3. Energy level diagram of GaAsBi/AlGaAs SQW for the three studied structures A, B, and C. ISBT for structure a is ISBT1_A, for structure B are respectively ISBT1_B, ISBT2_B, and for structure C are respectively ISBT1_C, ISBT2_C, SBT3_C.

Figure 4. The 3D electron density for structures A (a), B (b), and (c).

Figure 5. The absorption coefficient AC for structures A (a), B (b), and C (c) for doped and undoped GaAsBi/AlGaAs heterostructures.

Figure 6. The variation in the intensity difference of the absorption coefficient, ${\Delta }_{\mathit{\text{AC}}},$ between doped and undoped structures for the GaAsBi active layer thickness.

Figure 7. (a) 3D plot showing the variation of the absorption coefficient (AC) with frequency and active layer thickness at a fixed doping concentration (${\mathrm{N}}_{\mathrm{d}}=5\times {10}^{18}$). (b) 3D plot depicting the variation of the AC with frequency and active layer doping concentration at a fixed quantum well width (${\mathrm{L}}_{\mathrm{\text{QW}}}=7\hspace{0.17em}\mathrm{\text{nm}}$).

Figure 8. Structure C absorption coefficient at different doping levels of GaAsBi quantum well.

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Data availability

All results exist in the main manuscript.