Lecture 5

What function describes the probability of filling with electrons of any level?

• Fermi-Dirac

• Bose- Einstein

• Poisson

What transitions are characterized by the fact that the momentum of the electron differs from the momentum of the hole?

• Indirect transitions

• Direct transitions

• Intraband transitions

The time of the superposition of electrons and holes Fermi levels in the p - n junction is ...

• 10^-4 s

• 10^-12 s

• 10^-8 s

Can lasers based on homojunction operate continuosly?

• No

• Only at high temperature

• Only at low temperature

What is the reason for the photon localization in the p-n junction region in double heterojunction lasers?

• Total internal reflection

• Population inversion

• External voltage application

The number of charge carriers in heterojunction lasers is ... in comparison with homojunction lasers.

• higher

• lower

• comparable

If a number of QD layers in the active layer increases, the threshold current ...

• Increases

• Decreases

• Does not change

What are the characteristics of the third generation Q-LED?

• Limited brightness

• Maximum efficiency = 5%

• Two mechanisms of luminescence excitation - electron injection and FRET

What are the characteristics of the first generation Q-LED?

• FRET is the main mechanism for the excitation of luminescence

• The main mechanism of luminescence excitation is the injection of charge carriers

• Two mechanisms of luminescence excitation - electron injection and FRET

What are the characteristics of the second generation Q-LED?

• Non-shell QDs were used

• The presence of an organic layer leads to instability in air

• Low efficiency (<0.1%)