2024年6月2日发(作者：)

光电子学_南京邮电大学中国大学mooc课后章节答案期末考试题库

2023年

1. Photogeneration occurs in the neutral region. The electron has to diffuse to

the depletion layer and then roll down the energy drift across the SCL.

参考答案:

正确

2. Photogeneration inside the LED generates an electron and a hole.

参考答案:

错误

3. The fifth valence electron can be readily freed by thermal vibrations of the Si

lattice.

参考答案:

正确

4. The area under pE(E) versus E is not the hole concentration.

参考答案:

错误

5. vdh = Drift velocity of the holes

参考答案:

正确

6. Wavelengths greater than roughly lg are not absorbed (by band-to band

transitions).

参考答案:

正确

7. When it moves a distance dx, work must be done by the external circuit. In

time dt, the electron drifts a distance dx and does an amount of work eEdx

参考答案:

正确

8. The electron is notacted on by the forceeEof the electric field.

参考答案:

错误

9. The cavity in Vertical Cavity Surface Emitting Lasers is not vertical.

参考答案:

错误

10. External photocurrent due to the motion of this photogenerated electron is

ie(t).

参考答案:

正确

11. If EF is close to the conduction band (CB) edge, Ec, it results in an n-type, and

if it is close to the valence band (VB) edge, Ev, it results in a p-type

semiconductor.

参考答案:

正确

12. An electron and hole pair (EHP) is photogenerated at x = y. The electron and

the hole drift in opposite directions with drift velocities vh and ve

参考答案:

错误

13. An open circuit pn junction under illumination generates an open circuit

voltage Voc.

参考答案:

正确

14. The pn junction in open circuit. The photogenerated electron and hole roll

down their energy hills (drift) but there is a voltage Voc across the diode that

causes them diffuse back so that the net current is zero.

参考答案:

正确

15. Light from an optical fiber is coupled into the active region of the laser

structure. As the radiation propagates through the active layer, optically

guided by this layer, it becomes amplified by the induced stimulated

emissions, and leaves the optical cavity with a higher intensity.

参考答案:

正确

16. Traveling wave (TW) semiconductor optical amplifier: The ends of the

optical cavity have antireflection (AR) coatings so that the optical cavity does

not act as an efficient optical resonator, a condition for laser-oscillations.

参考答案:

正确

17. The cross section of Vertical Cavity Surface Emitting Lasers is circular.

参考答案:

正确

18. The mode field diameter is normally larger than the active layer thickness

and the radiation spreads into the guiding layer.

参考答案:

正确

19. Partially reflected waves at the corrugations can only constitute a reflected

wave when the wavelength satisfies the Bragg condition.

参考答案:

正确

20. Rate of electron injection by current I = Rate of spontaneous emissions - Rate

of stimulated emissions

参考答案:

错误

21. When the laser is in a steady state, Rate of coherent photon loss in the

cavity= Rate of stimulated emissions

参考答案:

正确

22. Power Conversion Efficiency=Optical output power / Electric input power

参考答案:

正确

23. Extraction efficiency = (Total loss)/(Loss from the exit cavity end)

参考答案:

错误

24. The width of the CB is called the electron affinity χ.

参考答案:

正确

25. The interactions between the Si atoms and their valence electrons result in

the electron energy in the crystal falling into two distinct energy bands called

the valence band (VB) and conductions band (CB).

参考答案:

正确

26. At sufficiently high diode currents corresponding to high optical power, the

operation becomes single mode.

参考答案:

正确

27. In LED, most of the light is in the active region.

参考答案:

错误

28. In multiple quantum well (MQW) heterostructure laser diode, electrons are

injected by the forward current into quantum wells.

参考答案:

正确

29. The density of sates g(E) is a step-like function, and is finite at E1 and E1¢.

参考答案:

正确

30. A buried heterostructure laser diode for telecom applications: The active

layer (InGaAsP) is surrounded by the wider bandgap, lower refractive index

InP material. Layers are grown on an InP substrate.

参考答案:

正确

31. A double heterostructure semiconductor laser device has its active region

buried within the device in such a way that it is surrounded by low refractive

index materials rendering the active region as a waveguide.

参考答案:

正确

32. Robert Hall and his colleagues, while working at General Electric's Research

and Development Center in New York, were among the first groups of

researchers to report a working semiconductor laser diode in 1962.