High-Rate Epitaxial Growth of Silicon Using Electron Beam Evaporation at High Temperatures

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript titled “High-rate epitaxial growth of silicon by electron beam evaporation deposition at high temperatures” presented by Marit Stange, Tor Olav Sunde, Runar Dahl-Hansen, Kalpna Rajput, Joachim Seland Graff, Branson Belle and Alexander Ulyashin.

• Non-ultra-high vacuum conditions: Please, specify the pressure instead.
• Electron beam (e-beam) deposition. Looks that the “evaporation” is missed (see Title).
• Line 14: Raman died, Raman spectroscopy.
• Abstract demands corrections.

The presented manuscript could be accepted for publication. Some corrections are demanded. Some terms sound non-scientifically.

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Comment 1: Non-ultra-high vacuum conditions: Please, specify the pressure instead.

Answer:  Yes, we have addressed this.

"In this paper high-rate (~1.5 mm/min) growth of Si films on top of Si supporting substrates with (100) crystallographic orientation at 600 °C, 800 °C and 1000 °C under non-ultra-high vacuum conditions using electron beam (e-beam) deposition is performed" is replaced by "This paper describes high-rate (~1.5 mm/min) growth of Si films on Si supporting substrates with (100) crystallographic orientation at 600 °C, 800 °C and 1000 °C in a vacuum environment of ~1x10^-5 mbar using electron beam (e-beam) evaporation"

 

Comment 2: Electron beam (e-beam) deposition. Looks that the “evaporation” is missed (see Title).

Answer: Since Electron beam evaporation is commonly used for the definition of the technological process, we think Electron beam evaporation is more correct than electron beam evaporation deposition, so we have removed "deposition" from the title.

 

Comment 3: Line 14: Raman died, Raman spectroscopy.

Answer: We for sure agree with this ?, and corrections are done accordingly.  

Line 18-19 and keywords: "Raman" replaced by "Raman spectroscopy", and "RAMAN" replaced by "Raman spectroscopy" in line 16.

 

Comment 4: Abstract demands corrections.

We have done some corrections to the abstract. The changes are marked with yellow in attachment (II)

 

Comment 5: The presented manuscript could be accepted for publication. Some corrections are demanded. Some terms sound non-scientifically.

Moderate editing of English language required

Answer: We have done editing of the English language. Since no examples of "non-scientific terms" are given by the reviewer, it is a bit difficult to address this, but we have tried

 

Examples:

"More efforts to improve the process conditions to control and reduce the defect density should be applied"

has been substituted with

"Additional initiatives aimed at enhancing the process conditions to effectively manage and decrease defect density need to be implemented".   

 

"This result can be considered as an initial and indicative proof of concept showing the feasibility to perform lift off process for e-beam deposited Si epi-layers deposited on supporting Si substrates with porous Si weak layer."

has been substituted with

"This result serves as an initial and indicative proof of concept, demonstrating the feasibility of executing a lift-off process for e-beam deposited Si epi-layers deposited on supporting Si substrates with a porous Si weak layer."

 

"Further optimizations of the lift of process for the e-beam deposited layers are required, but initial results show that this is doable and the observed onset of exfoliation can be considered similar to the case of the blistering phenomena [27], which was analysed in the past as an indication of a feasibility to realise the "Smart-cut" process"

has been replaced by

"Improvements to the lift-off process for e-beam deposited layers are needed, but these initial findings indicate its feasibility. The observed initiation of exfoliation is akin to the blistering phenomenon [27], previously studied as an indicator of the feasibility to implement the "Smart-cut" process."

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

1) The study successfully demonstrates the growth of p-doped Si films on Si (100) substrates at temperatures ranging from 600 to 1000 °C using high-rate e-beam evaporation. Notably, fully crystalline Si layers with a thickness of approximately 50 µm can be achieved at a deposition rate of ~1.5 µm/min at 1000 °C. This highlights the potential of e-beam evaporation as a promising and cost-effective alternative to conventional CVD for the growth of epi-Si layers and, potentially, epi-Si wafers.

2) While the deposition rate of e-beam deposited layers rivals that of atmospheric pressure CVD processes, Secco etch experiments expose a notable density of extended defects at elevated temperatures. This underscores the necessity for further optimization in the growth of Si layers and epi-wafers using e-beam evaporation. Future studies should explore deposition temperatures up to 1200 °C, comparing results with CVD-based processes. Additionally, an in-depth analysis of the transferability of dopants (Boron, Gallium, Phosphorous) during e-beam evaporation is crucial, and in-situ doping using effusion cells may be necessary. Furthermore, the e-beam evaporation process should be examined for its potential to effectively remove Boron from the Si feedstock, and manufacturing processes like lift-off should be explored for producing epi-Si-based wafers.

Author Response

Comments and Suggestions for Authors

1) The study successfully demonstrates the growth of p-doped Si films on Si (100) substrates at temperatures ranging from 600 to 1000 °C using high-rate e-beam evaporation. Notably, fully crystalline Si layers with a thickness of approximately 50 µm can be achieved at a deposition rate of ~1.5 µm/min at 1000 °C. This highlights the potential of e-beam evaporation as a promising and cost-effective alternative to conventional CVD for the growth of epi-Si layers and, potentially, epi-Si wafers.

 

2) While the deposition rate of e-beam deposited layers rivals that of atmospheric pressure CVD processes, Secco etch experiments expose a notable density of extended defects at elevated temperatures. This underscores the necessity for further optimization in the growth of Si layers and epi-wafers using e-beam evaporation. Future studies should explore deposition temperatures up to 1200 °C, comparing results with CVD-based processes. Additionally, an in-depth analysis of the transferability of dopants (Boron, Gallium, Phosphorous) during e-beam evaporation is crucial, and in-situ doping using effusion cells may be necessary. Furthermore, the e-beam evaporation process should be examined for its potential to effectively remove Boron from the Si feedstock, and manufacturing processes like lift-off should be explored for producing epi-Si-based wafers.

Answer: Thank you for your suggestions. The suggested text from the reviewer has been implemented in the conclusions. (Please see yellow marks in attached document with highlighted improvements)

 

Reviewer 3 Report

Comments and Suggestions for Authors

 

The electron beam evaporation deposition of epitaxial growth of silicon shows great potential for future electronics, and the article provides strong scientific evidence in support of this direction. However, there are some necessary revisions before acceptance for publication, as outlined below.

1.       There is a typographical error in Raman Figure 3 (referred to as Figure 2 in the article). The numbering of all figures beyond the 2nd figure needs correction.

2.       In Figure 3 (grey area Raman), it appears that fitting was performed to incorporate the defective crystalline phase, particularly the 800°C peak. Could the authors elucidate in the article how the chemical environment differs between crystalline and non-crystalline Si in their films?

 

3.       The authors should include information on normalization and smoothening methods in the revised manuscript.

Author Response

Comment 1: There is a typographical error in Raman Figure 3 (referred to as Figure 2 in the article). The numbering of all figures beyond the 2nd figure needs correction.

Answer: Thank you for making us aware of this. It is done.

Comment 2:  In Figure 3 (grey area Raman), it appears that fitting was performed to incorporate the defective crystalline phase, particularly the 800°C peak. Could the authors elucidate in the article how the chemical environment differs between crystalline and non-crystalline Si in their films?

Answer:

I agree, this should be explained better. The following clarification has been included into article text:

The defective/mixed crystalline phase usually is attributed to microcrystalline Silicon [19, 20], which is formed in the grey parts of 600 °C and 800 °C films as a transition phase between amorphous and crystalline silicon during crystallization process. More investigations required to clarify the nature and reason for the formation of such areas, which have defective/mixed crystallinity phase. Such studies are outside the scope of this article. However, it can be concluded that higher deposition temperature fully eliminates formation of such defective/mixed crystallinity phase. 

Comment 3: The authors should include information on normalization and smoothening methods in the revised manuscript.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The current version is OK and could be accepted for publication

Reviewer 2 Report

Comments and Suggestions for Authors

 Accept in present form

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have taken care of all the comments and I would recommend the present submission for publication.