Theory of Electronic and Optical Properties of Atomically Thin Films of Indium Selenide by Samuel J. Magorrian

Author:Samuel J. Magorrian
Language: eng
Format: epub, pdf
ISBN: 9783030257156
Publisher: Springer International Publishing

Figure 3.3 summarises the few-layer (up to 10 layers) gaps obtained from scissor-corrected DFT calculations, from the HkpTB model with scissor and gap correction methods as described above, and from the tight-binding model of Chap. 2. The scissor-corrected DFT and HkpTB model are almost in agreement, with a small discrepancy arising between them as the HkpTB model struggles to replicate the light band-edge effective mass from DFT in the bulk, and consequently does not exactly reproduce the discretised few-layer bands and gaps. The gap correction method gives slightly smaller gaps for few-layer InSe, as expected from the increased effective mass in the bulk resulting from this method. Finally, motivated by the corrections applied here, we revisit the question of how to fit the tight-binding model in Chap. 2. The finding here is that while it is better to use a corrected monolayer parameter set, attempting to fit interlayer hopping parameters to scissor-corrected DFT—as was done for the tight-binding model—can give misleading results. We therefore compare the scissor-corrected tight-binding as presented in Chap. 2 with a ‘gap-corrected tight-binding model’—i.e. using the ‘S.C.’ monolayer tight-binding parameters from Table 2.​1, but with the interlayer hops taken as those fitted to uncorrected DFT in Table 2.​3. We see in Fig. 3.3 that while the scissor-corrected tight-binding model gives notably smaller gaps at larger numbers of layers, the gap-corrected tight-binding model very closely tracks the chosen HkpTB model result. While the scissor-corrected tight-binding model of Chap. 2 does not reproduce the expected gap for , the gap-corrected tight-binding model gets much closer, with a fit to Eq. (2.​11) giving a limiting value eV as well as an increased out-of-plane reduced mass of .1 The ‘TB G.C.’ parameter set may therefore be considered a useful choice.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.