Third Harmonic Generation at crystalline Si

[ChuHoang1610]

Dear Dr. Nick,

I am involved in a project that requires the simulation of THG from silicon under different doping and crystalline orientations. I have several questions regarding the possibility of using Lightwave Explorer for the simulation section.

1. Can this software simulate the THG reflected back from the surface, or is this only allowing transmission type? Because the experiment system I intend to build is a reflected type microscope @ 1550 nm, 80 mW. Below is my intended system configuration.
   

2. Can we add multiple stacks of materials? Let's say Si-Ge deposited on Si subtract? It would be nice if you could share some example simulations with us because I tried here and there in your software but could not find them.

This is the paper I want to replica the result using your software (just for reference) : "Yi Gao, Hyub Lee, Jiannan Jiao, Byung Jae Chun, Seungchul Kim, Dong-Hwan Kim, and Young-Jin Kim, "Surface third and fifth harmonic generation at crystalline Si for non-invasive inspection of Si wafer's inter-layer defects," Opt. Express 26, 32812-32823 (2018)," Especially about the result like Figure 2e and Figure 3

Best Regard,
Chu.

[NickKarpowicz]

Hi there,
sorry for the delayed response; I was traveling then had to take care of a lot when I got back.
Here's a short version of the answer, and I can add more a bit later...

A reflection geometry is possible in the FDTD propagation mode, which is more numerically taxing but should be ok as long as the crystal isn't too thick. I'll need a better implementation of silicon in the crystal database as well, using Lorenzian resonances to describe the refractive index and with the full chi3 tensor.

could you give a bit more info about your experimental configuration? How thick would the layers from which you want to reflect be?

Cheers,
Nick

[ChuHoang1610]

Dear Dr. Nick,

Thank you for your response!

1. About the thickness of Si crystal. Recently, I have been using a 280-um thick silicon wafer. You can refer to the table below for details of the silicon sample.

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Sample No.	Description	Dimension	Polishing	Dopant	Orientation
1	2-inch Silicon wafer	Dia: 2” x 0.28mm ±25μm	DSP	Un-doped	(111) ±0.5°
2	2-inch Silicon wafer	Dia: 2” x 0.28mm ±25μm	DSP	N-type/Phos-doped	(111) ±0.5°
3	2-inch Silicon wafer	Dia: 2” x 0.28mm ±25μm	DSP	P-type/Boron-doped	(111) ±0.5°
4	2-inch Silicon wafer	Dia: 2” x 0.28mm ±25μm	DSP	Un-doped/N Type	(100) ±0.5°
5	2-inch Silicon wafer	Dia: 2” x 0.28mm ±25μm	DSP	N-type/Phos-doped	(100) ±1°
6	2-inch Silicon wafer	Dia: 2” x 0.28mm ±25μm	-	P	100

2. I also ran some initial experiments: Silicon crystals with 100 orientations give 4-fold TH intensity modulation following the change in input polarization, while silicon 111 does not show any polarization dependency. We tried to do the simulation to understand this phenomenon where the sample was not good, or our experimental system had flaws because the prior paper showed that silicon 111 undoped still illustrates THG dependence on input polarization.

3. I am also interested in multiple-stack material. I measured some samples from the difference group, which is 0.8nm Ge epitaxy onto Si substrate, and it shows significant enhancement in THG. I also want to explain this phenomenon via simulation.

Hope to hear from you soon !

Best Regard,
Chu.