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Characterization of layered gallium telluride ( GaTe )

Characterization of layered gallium telluride ( GaTe ). Omotayo O Olukoya (Chabot College) PI : Oscar Dubon Mentor : Jose Fonseca Vega Lawrence Berkeley National lab. 0.8 1.6 2.4 3.2 nm. adapted from D. V. Rybkovskiy et al. , PRB (2011). Layered semiconductors.

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Characterization of layered gallium telluride ( GaTe )

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  1. Characterization of layered gallium telluride (GaTe) Omotayo O Olukoya (Chabot College) PI : Oscar Dubon Mentor : Jose Fonseca Vega Lawrence Berkeley National lab

  2. 0.8 1.6 2.4 3.2 nm adapted from D. V. Rybkovskiy et al., PRB (2011) Layered semiconductors Chalcogenide • Complex structure • Manipulate band-gap. • Recent discovery GaSe MoS2 GaTe (1.045 nm) Mak, K.F., et al.,Phys Rev Lett. 105, 136805 (2010).

  3. GaTe • What do we know? Monoclinic crystalline structure in bulk. parameter constant: a = 17.44 Å, b = 10.456 Å, c = 4.077 Å,ϒ = 104.4o b. Goes from monoclinic to hexagonal in thin films c. Direct band gap of 1.69 eVat room temperature. d. P - type • What to look for?

  4. Method • Substrate treatment • 300 nm of thermally oxidized SiO2on Si was used. • Ultra sonication • Isopropyl alcohol • Acetone • Oxygen plasma • Standard RCA cleansing method

  5. Method cont. • Mechanical exfoliation • Scotch tape method was develop by Andre Geim • Transfer • Optical microscopy

  6. Method cont. • Atomic Force microscopy (AFM) • Tapping mode AFM images 8 nm

  7. Method cont. • Raman spectroscopy • A 15mW Ar ion laser (514.5 nm) was used. • Photoluminescence spectroscopy (PL) • A 488 nm blue laser

  8. Raman result • Raman spectra cont. a. New peaks between 140 & 280 of Raman shift

  9. Raman’s result cont. • Raman spectra b. Horizontal shift

  10. PL result • Correlation between laser intensity and counts

  11. PL result cont. • Correlation between thickness and count

  12. Conclusion • GaTe exhibits some anisotropic features. • It will take further research to know what properties are actually isolated from bulk. • Great chances of being able to cleave down to a monolayer on SiO2 substrate.

  13. Next step • Cleave down to a monolayer • Take more Raman • Take low temperature PL • Devices and application?

  14. Acknowledgment • Prof Oscar Dubon (PI) • Jose Fonseca Vega (mentor) • Dubon’sGroup • Alex Luce (PL) • Erick Ulin-Avila • Dr. SharniaArtis • Shuk H Chan • Center for Energy Efficient Electronics (E3S) • National Science Foundation (NSF) Q & A ?

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