# Im convuesed help

1. Aug 31, 2009

### weds

hi guys im quit confused n i have some problem that i realy need some one 2 solve them and 4 me
the first prob

1. A one dimensional infinite potential well with a width of 12A contains an electron.
a. Calculate the first two energy levels that the electron may occupy
b. If an electron drops from the second energy level to the first, what is the
wavelength of a photon that might be emitted?

2nd one

If the temperature is 300K, determine the number of energy states available in GaAs
between:
a. Ec and Ec+kT
b. Ev-kT and Ev

and the last one

Plot the function for Fermi-Dirac distribution for eV E E eV
F − 0.5 ≤ ( − ) ≤ 0.5 for:
a. T=200K
b. T=300K
c. T=400K
thanx

Last edited: Aug 31, 2009
2. Aug 31, 2009

### drizzle

hey weds, welcome to PF

why don’t you show the related equations, and show your attempt to solve these problems, we’ll then help you

3. Aug 31, 2009

### weds

oh i actually solve the first and the related equation 4 it is
• Total energy
h(square)x n(square)x π(square) / 2m a(square).....where a is the potential width which = 12x10(power of -10)
substitute the values and i've got the answers

for the next quastion the related equation is
• Density of state function in conduction band
g Ec =(4π(2m(power of 3/2)) /h(power 3))x((root of)E-Ec)

• Density of state function in valence band
g Ev =(4π(2m(power of 3/2)) /h(power 3))x((root of)E-Ev)

bt i dont knw how to substitute the value from the problem to the equqtion

for the last prob
the related equation is
• Fermi-Dirac distribution function:
f ( E) =1/exp(E-Ef/kT)
thanx