Purpose of substrate in semiconductor lasers

  • #1
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What is a purpose of a substrate in an electronic device? In particular semiconductor lasers, why is it made of semiconductor?

Thank you.

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  • #2
In many cases the substrate is one of the electrodes. Otherwise it is chosen because the active layers can be easily grown epitaxially on the substrate material, or because the active components can be produced by locally doping the substrate, e.g. by ion implantation. Sometimes the substrate acts as a heat sink. Last but not least, simultaneously producing a large number of tiny devices on a common substrate is a neat way of holding everything together and connected.

I'm sure I forgot some other good reasons.
 
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  • #3
I think M Quack covered it pretty well. For example, look at MOSFETs - very tiny transistors. The "substrate" is often Silicon for things like NAND flash memory, and areas of it are either n or p type doped for various reasons that you can look up.
 

1. What is the purpose of a substrate in a semiconductor laser?

The substrate in a semiconductor laser serves as the foundation upon which the laser is built. It provides mechanical support and stability, as well as a surface for the deposition of the layers that make up the laser structure.

2. How does the substrate affect the performance of a semiconductor laser?

The substrate can affect the performance of a semiconductor laser in several ways. It can impact the crystal structure and quality of the layers grown on top, which can affect the electrical and optical properties of the laser. It can also affect the thermal conductivity and heat dissipation capabilities of the laser, which can impact its power output and efficiency.

3. What are the common materials used as substrates for semiconductor lasers?

Some common materials used as substrates for semiconductor lasers include gallium arsenide (GaAs), indium phosphide (InP), and gallium nitride (GaN). These materials have similar crystal structures to the semiconductor layers grown on top, allowing for a good match and minimizing defects.

4. Can the choice of substrate affect the wavelength of a semiconductor laser?

Yes, the choice of substrate can affect the wavelength of a semiconductor laser. This is because the lattice constant of the substrate can influence the lattice constant of the layers grown on top, which in turn affects the bandgap and thus the emitted wavelength of the laser.

5. Are there any considerations to keep in mind when selecting a substrate for a semiconductor laser?

When selecting a substrate for a semiconductor laser, some key considerations include the lattice and thermal match to the layers grown on top, the desired emission wavelength, and the mechanical and thermal properties needed for the intended application. Cost and availability may also be factors to consider.

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