Recent content by Jalo

Hi, I'm studying p-i-n photodiode (PD) at the moment and understand that the photodiode's response will depend on the frequency of the light signal going into it. I am struggling however to understand the concept of bandwidth, and why is it that the photocurrent at the PD decreases with higher...

What I don't understand is how is it different to excite the sample with a 300nm photon vs a 600nm photon for a material whose main transitions take place at for example 800nm, since both have a higher energy than the main transition that takes place in the sample. Shouldn't both photons be...

If I'm exciting on a wavelength lower than where my emission is shouldn't I always obtain luminescence, with the extra energy from the inciding photons leading to non radiative relaxation of the electrons until they match an energy equal to radiative transitions of the material?

I'm not sure I understand what information we can get from Photoluminescence Excitation (PLE) that we don't get from regular PL. Let's imagine we have a sample with emissions between 700nm and 850nm. If I'm not mistaken in a typical PL experiment you'd just use a laser source with a wavelength...

Homework Statement Why do supposedly forbidden transitions appear in experimental spectrums? Homework EquationsThe Attempt at a Solution I'm really puzzled as to why they appear. Can it be due to transitions on higher energy levels that happen to be equal to the forbidden ones?

Hello. I'm currently taking a physics course that gives me the freedom to take any subject related to semiconductors and do some research on it, presenting it at the end of the semester. I know I want to do something related to programming, but I'm having a hard time finding a theme. Hence me...

Homework Statement The atomic mass of Niquel is 58.7 amu (atomic mass unit), and it's density (at 90ºC) is 8.86 g/cm³. (a) Find the distance from one atom to the closest one from him.Homework Equations 1 amu = 1.66053*19⁻²⁷ The Attempt at a Solution I started by finding the number of atoms...

Thank you very much! I was so close, should have figured it out! :P

Homework Statement Given the following hamiltonian and the observable \widehat{B} find the possible energy levels (a is a real constant). If the state is in it's fundamental state what's the probability of measuring b_{1}, b_{2} and b_{3}? Homework Equations The Attempt at a...

I forgot that I was only interested in the |->_{z} component. Regarding the factor of 2, I'll correct it. However my major issue has been resolved, so thanks!

Homework Statement An alkali atom, on it's fundamental state, passes through a Stern-Gerlach apparatum, which will only transmit atoms with their spins aligned along the +z direction. After that the atoms travel, during a finite time τ, through a region of constant magnetic field...

Homework Statement Given the following circuit find the input resistance as seen through vo. Homework Equations The Attempt at a Solution To solve this problem I started by drawing the signal equivalent circuit: As we can see the voltage vgs = vi - vo. To find the input resistance I used...

Thanks! I finally got it right. VG = VDD (R2-R1)/(R2+R1) VGS = VG - RsID + VDD ID = k(VGS-VT)2 Replacing VGS in the expression (1) I managed to find the correct solution. I still have one doubt tho. The value of λ is very small, only 0.02 V-1. When the value is that low can I simply...

Sorry, I meant to write 2VDD instead of only VDD.

Homework Statement Given the following circuit find the bias point (VDS,IDS). Homework Equations The Attempt at a Solution The first thing I did was find the value of VG, the voltage from the gate of the mosfet to the -VDD source. VG = VDD * R2/(R1+R2) To find the...