I want to grow nano-spheres/nanorods/nanowires of a metal in the glass substrate in the sizes of around 80-120 nm radius using that metal's powders through thermal evaporation. The boiling temperature of the metal is 880 C at 1 atm. Now, I want to know how can I fix the appropriate vacuum base pressure, experiment time pressure and heating temperature to make sure that I get my required sized (80-120 nm radius) nanosphere/nanowires.
Can anyone pls suggest me any paper/book/handbook where I can know all the details of this?
And the other thing is, almost all the literature I read, I found people used metal powder for growing nanowires/nanospheres. Can I use bulk metal instead of powder to grow nanospheres/nanowires?
Thanking you in advance
Dear Shaikat,
this all depends very much on the apparatus you are using and the materials system you are looking at. The base pressure is typically given by the pumping system and leakage rates, the working pressure depends on the gas flux you use. In some set-ups butterfly valves are used.
Powder or bulk: the only good reason for using powders is that you can easily mix them with an other substance, in order to reduce the metal. This is for instance done in VLS growth of ZnO nanowires, where ZnO powder is mixed with graphite powder to reduce ZnO to Zn (by formation of CO or CO2) which is then transported to the growing ZnO nanowire, where Zn oxidises again.
I hope this answers your question?
Jörg Lindner
Shaikat,
for a controllable process you might need a reactor that is pumped on one side while a carrier gas is supplied on the other side. Coming from the inlet, the carrier gas would pass your heated source and carry the evaporated material towards your substrate before flowing into the outlet. In this particular case you will need to control the flow of your carrier gas with a mass flow controller (MFC) and then use the already mentioned butterfly valve between the outlet and the vacuum pump. The valve needs to be controlled, based on the measured pressure in the chamber. Such a pressure control (e.g. MKS) system is typically used in MOCVD machines.
As for the temperature control, I suspect that it's most important to control your substrate temperature in order to be able to specify your desired growth conditions. Methods involving a lamp heating, a filament or RF heating typically utilize a thermocouple which is monitored by a PID controller that in turn regulates the power of the heater.
However, such a setup goes beyond a classical thermal evaporation process in terms of complexity.
Greetings,
Kamil
There is hard and fast rule . For sphere you need fast evaporation rate and faster cooling . For rod you need unique temperature gradient and vapor pressure .
Prof Pramanik
Sorry . There is no hard and fast rule . For sphere you need fast evaporation rate and faster cooling . For rod you need unique temperature gradient and vapor pressure .
Prof Pramanik
Though peoples are using metal powder for growing nanowires/nanospheres., bulk metal are much useful to grow nanospheres/nanowires. You may read our research papers published in Cryst. Growth & Design, Nanotechnology, Nanoscale, Appl. Phys. Lett., Solar Energy Mater. Solar Cells, and Phys. Chem. Chem Phys., . We have used bulk metal.
Thank you very much to all of yours helping.
Can anyone of you please suggest me any book/any other way where I can know all the details of the process.
Like what should be the exact temperature for me, the base and experiment pressure, distance between the metal and the substrate, the temperature gradient between the metal and the substrate and most imporantly, i want to know how these nanospheres/nanowires form, how can I control the experiment etc.
So can anyone pls suggest me any book regarding this things? I will be very much grateful
- Badges
- Science topic
- Similar topics
- Engineering
- Materials Engineering
- Annealing
- Metallurgy
- Metals