Finally I get what i was looking for

Photocurrent Measurement can be seen as easiest of experiments to do..i beg to differ especially when dealing with lots of unknowns such as devices which have defects. You will spend days probing but you won't get what you are looking for...But perserverance pays big time.. i have never seen beautiful spectrum like the one i saw today.. I can see excitonic states at work, excitation between energy levels in quantum well as well as the barrier materials...so today is exciting day for me...i can see electrons in the valence band gobbling up incoming photons and get very excited such that they jump over the band gap (that is absorption). while sending in photons of increasing energy (from higher wavelength (low energy) to lower wavelength (higher energy)), electrons get busy absorbing incoming photons and jump to create photo-induced current.