Cthugha said:What exactly do you mean by position of the gap?
If you mean the band gap energy of GaAs, it is about 1.42 eV at room temperature, but shows strong temperature dependence (have a look at the Ioffe semiconductor database if you want to know the exact numbers).
If you mean the position of the GaAs layer it is located wherever you grow it and as thick as you grow it.
Cthugha said:I suppose you mean the band gap energies by "position".
That question cannot be answered in a general manner as AlGaAs is short for [tex]Al_XGa_{1-X}As[/tex]. The properties of AlGaAs depend strongly on the Aluminium content. The band gap at room temperature varies between the band gaps of pure GaAs at x=0 and pure AlAs at x=1, which are 1.42 and 2.16, respectively. Unfortunately the dependence is not linear and not trivial. Also, the nature of the band gap changes when increasing x. For x larger than roughly 0.4 the band gap becomes indirect for example. Both band gaps will of course also vary when the temperature is changed, so that the difference between the band gaps is also a non-trivial function of temperature and the Al-content.
wdlang said:you missed my question
i do not care the specific materials, i do not care the temperature dependence
the question comes from the quantum well
what is the depth of the quantum well for the electron?
Cthugha said:Sigh, ok...you are new to this I assume...the depth of the quantum well is given by the energy gap (or conduction band) differences of the two materials used and therefore the well depth intrinsically depends on temperature and material composition. For square wells it is on the order of 330 meV for x=0.3 as LewisEE pointed out, it is about 150 meV for x around 0.1 to 0.15.
There is no "THE" depth of a quantum well.
chrisbaird said:In order to calculate quantum well depths, you have to know the band gaps and the band alignments. The band alignments are rather hard to come by from scratch, put typical values are published. For band alignments, I use the http://prb.aps.org/abstract/PRB/v39/i3/p1871_1" if you know the parameters.
wdlang said:but the principle is the chemical potentials are the same?
wdlang said:is there any good reference?
wdlang said:yes, i am absolutely new to this field
is there any good reference?
i guess the temperature dependence of the well depth comes from the temperature dependence of the chemical potentials. is that right?
A semiconductor quantum well is a thin layer of a semiconductor material that is sandwiched between two layers of a different semiconductor material. This structure creates a potential well that confines electrons and holes, allowing for quantum effects to occur.
Quantum wells work by creating a barrier for electrons and holes to move through. When the electrons and holes are confined within the well, they exhibit quantum properties such as quantized energy levels and tunneling. This makes quantum wells useful for various applications such as lasers and transistors.
One of the main advantages of using semiconductor quantum wells is their controllable bandgap. By adjusting the thickness of the well layer, the bandgap can be tuned to specific energy levels, making them useful for optoelectronic devices. They also have high carrier mobility and can operate at room temperature.
Some common materials used for semiconductor quantum wells include gallium arsenide (GaAs), gallium nitride (GaN), and indium phosphide (InP). These materials have suitable bandgaps for optoelectronic applications and can be combined to create heterostructures with desired properties.
Semiconductor quantum wells have a wide range of applications, including optoelectronics, quantum computing, and sensing. They are commonly used in laser diodes, LEDs, and solar cells. They also play a crucial role in the development of quantum dot devices and quantum cascade lasers.