<abstract xmlns="http://www.w3.org/1999/xhtml">Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by thermal evaporation technique under high vacuum conditions from the prepared bulk samples. Effect of Bi substitution on surface morphology, electrical and optical properties of BixSe1-x thin films was studied. X-ray diffraction studies showed the formation of nanocrystalline clusters at Bi concentration x = 10. Formation of these clusters resulted in a rough surface which was confirmed by AFM measurements. The film surface was smooth, with RMS roughness of 0.0124 nm for Bi5Se95. For Bi10Se90, the RMS roughness increased to 3.93 nm indicating the formation of Bi2Se3 clusters. A simple hot probe technique showed a transition from p-type to n-type due to Bi incorporation. Charge transport mechanisms were investigated by temperature dependent DC electrical conductivity measurements in the temperature range of 209 K to 313 K. Electrical activation energy (ΔE) of the films with different Bi concentrations was found to exhibit a notable change at the p to n transition. At low temperature, the conduction was in reasonable agreement with Mott’s condition of variable range hopping. Mott parameters and the density of localized states near Fermi level were evaluated and correlated with the structural changes resulting from Bi addition. In addition, a red shift of the optical absorption edge of the films under study caused by Bi-Se substitution was observed. Slight changes in the optical parameters were observed with the <italic>γ</italic>-irradiation. Addition of Bi atoms could be used to tailor the structural, electrical and optical properties of chalcogenide materials such as junctionless photovoltaic devices.</abstract>

Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by thermal evaporation technique under high vacuum conditions from the prepared bulk samples. Effect of Bi substitution on surface morphology, electrical and optical properties of BixSe1-x thin films was studied. X-ray diffraction studies showed the formation of nanocrystalline clusters at Bi concentration x = 10. Formation of these clusters resulted in a rough surface which was confirmed by AFM measurements. The film surface was smooth, with RMS roughness of 0.0124 nm for Bi5Se95. For Bi10Se90, the RMS roughness increased to 3.93 nm indicating the formation of Bi2Se3 clusters. A simple hot probe technique showed a transition from p-type to n-type due to Bi incorporation. Charge transport mechanisms were investigated by temperature dependent DC electrical conductivity measurements in the temperature range of 209 K to 313 K. Electrical activation energy (ΔE) of the films with different Bi concentrations was found to exhibit a notable change at the p to n transition. At low temperature, the conduction was in reasonable agreement with Mott’s condition of variable range hopping. Mott parameters and the density of localized states near Fermi level were evaluated and correlated with the structural changes resulting from Bi addition. In addition, a red shift of the optical absorption edge of the films under study caused by Bi-Se substitution was observed. Slight changes in the optical parameters were observed with the γ-irradiation. Addition of Bi atoms could be used to tailor the structural, electrical and optical properties of chalcogenide materials such as junctionless photovoltaic devices.

Optical and electrical characterization of BixSe1−x thin films

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Optical and electrical characterization of BiSe thin films

Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by...

Composition	Bulk		Thin film
	Se [at.%]	Bi [at.%]	Se [at.%]	Bi [at.%]
^Bi5^Se95	94.96	5.04	94.79	5.21
Bi10Se90	90.39	9.61	90.03	9.97

Composition	ΔE_σ[eV]	σ_o[Ω.cm] ⁻¹	ΔE₁ [eV]	σ₁ [Ω.cm] ⁻¹
Se	0.99±0.12	3.9 × 10¹⁰	0.87±0.04	3.3 × 10¹¹
Bi₅Se₉₅	0.03±0.03	0.69	0.12±0.002	0.2 × 10²
Bi₁₀Se₉₀	0.14± 0.02	0.8 × 10³	0.09± 0.004	0.15 × 10³

Composition	E_T eV	E_e eV	B_1/2 (eV.cm)^−1/2
Se	1.8±0.05	0.2±0.01	978.72
Bi₅Se₉₅	0.87±0.05	0.21±0.03	655.27
Bi₁₀Se₉₀	0.65±0.05	0.52±0.03	245.38

Composition	A K^1/4	T_o K	σ_ho Ω⁻¹.cm⁻¹	α cm⁻¹	N(E_f) eV⁻¹.cm⁻³	R_h cm	W me V	αR
Se	20.65	1.8 × 10⁵	2 × 10²	2 × 10⁶	1.021 × 10²¹	3 × 10⁷	8	8.8 × 10²
Bi₅Se₉₅	7.21	2.7 × 10³	0.1 × 10²	1.4 × 10⁴	6.87 × 10²²	3.6 × 10⁻⁷	0.075	0.6
Bi₁₀Se₉₀	5.61	9.9 × 10²	8.1 × 10	5.7 × 10⁴	1.87 × 10²³	2 × 10⁻⁷	0.15	2.8

Optical and electrical characterization of Bi_xSe_1−x thin films

Article Category: Research Article

Online veröffentlicht: 27. Juni 2016

Seitenbereich: 460 - 467

Eingereicht: 21. Dez. 2015

Akzeptiert: 10. März 2016

DOI: https://doi.org/10.1515/msp-2016-0052

Schlüsselwörter
chalcogenides, electrical conductivity, optical properties, γ-radiation

© Wroclaw University of Technology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

EDX data for BixSe1−x system

DC electrical parameters of BixSe1−x system.

Values of optical parameters of BixSe1−x system

DC electrical parameters of BixSe1−x system

Optical and electrical characterization of BixSe1−x thin films

Article Category: Research Article

Online veröffentlicht: 27. Juni 2016

Seitenbereich: 460 - 467

Eingereicht: 21. Dez. 2015

Akzeptiert: 10. März 2016

DOI: https://doi.org/10.1515/msp-2016-0052

Schlüsselwörterchalcogenides, electrical conductivity, optical properties, γ-radiation

© Wroclaw University of Technology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

EDX data for BixSe1−x system

DC electrical parameters of BixSe1−x system.

Values of optical parameters of BixSe1−x system

DC electrical parameters of BixSe1−x system

Optical and electrical characterization of Bi_xSe_1−x thin films

Schlüsselwörter
chalcogenides, electrical conductivity, optical properties, γ-radiation