What is the principle involved in GaAs laser?
When a p-n junction diode is forward biased, the electrons from n – region and the holes from the p- region cross the junction and recombine with each other. During the recombination process, the light radiation (photons) is released from a certain specified direct band gap semiconductors like Ga-As.
What is gallium arsenide laser?
The aluminium gallium arsenide laser is a diode laser, having similar characteristics as that of the aluminium gallium indium phosphide laser. The structure of AlGaAs is the same as gallium arsenide, but with a larger band gap. The wavelength emitted by these laser diodes falls into the infrared region.
What type of semiconductors are preferred in lasers?
Compound semiconductors, especially III-V compound semiconductors, are well suited for semiconductor lasers. The most basic, necessary condition required of laser materials is, of course, that the input energy can be converted into light energy with a reasonably high efficiency.
Why do we prefer GaAs for laser diodes?
Another advantage of GaAs is that it has a direct band gap, which means that it can be used to absorb and emit light efficiently. Silicon has an indirect band gap and so is relatively poor at emitting light.
How is semiconductor laser different from other lasers?
Unlike other lasers, semiconductor laser does not need mirrors to obtain the reflectivity needed to produce feedback mechanism. Reflection from the cleaved ends of the semiconductor chip is enough to produce lasing.
What is homojunction semiconductor laser?
Homojunction means the laser devices use the same material for both the p and n sides of the junction. The output power increases with the volume of the active layers, linear or stacked diode laser arrays can generate up to 20W cw and peak power up to 100W in quasi-CW operation.
What type of semiconductor is GaAs?
Gallium arsenide is a type III/V semiconductor, with high electron mobility and a high saturated electron velocity compared to silicon, enabling transistors made of gallium arsenide to function at frequencies over 250 GHz.
What are laser diodes made of?
The laser diode is made of two doped gallium arsenide layers. One doped gallium arsenide layer will produce an n-type semiconductor whereas another doped gallium arsenide layer will produce a p-type semiconductor. In laser diodes, selenium, aluminum, and silicon are used as doping agents.
Why is GaAs preferred over silicon?
The GaAs is better inspite of its higher band gap than Si because it absorbs relatively more energy from the incident solar radiation being of relatively hogher absorption coefficient.
What is GaAs semiconductor?
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a zinc blende crystal structure. GaAs is often used as a substrate material for the epitaxial growth of other III-V semiconductors, including indium gallium arsenide, aluminum gallium arsenide and others.
What are the principles of the AlGaAs laser diode?
A high laser efficiency demands that the light and injected charge carriers be confined as closely as possible to the same volume. As illustrated in Figure 7, the AlGaAs Laser Diode consists of a double heterojunction formed by an undoped (or lightly p-doped) active region surrounded by higher bandgap p and n AlxGa1-xAs cladding layers.
What is the GAAs of the Al XGA 1-xas diodes?
The GaAs refractive index at these wavelengths is n = 3.5 while the refractive index of the Al xGa 1-xAs cladding layers is slightly smaller. The Figure 8 indicates the electromagnetic field distribution due to the heterostructure.
Which is better for GaAs silicon or gallium arsenide?
GaAs advantages. Some electronic properties of gallium arsenide are superior to those of silicon. It has a higher saturated electron velocity and higher electron mobility, allowing gallium arsenide transistors to function at frequencies in excess of 250 GHz. GaAs devices are relatively insensitive to overheating,…
Why is GaAs a good substrate for integrated circuits?
Because of its wide band gap, pure GaAs is highly resistive. Combined with a high dielectric constant, this property makes GaAs a very good substrate for Integrated circuits and unlike Si provides natural isolation between devices and circuits.
