Choose some sentences from the text and transform them using Gerundial Construction

For example: Let us apply the theory of negative and positive carrier to this diode. – Our applying the theory of negative and positive carrier to this diode helps us to understand the processes better.

SPEAKING

Summarize the text “Operation of a Semiconductor Junction Diode” in 150 words using at least 4 cases of Gerund and Gerundial Construction.

Act as an interpreter.

c) Translate the summary given by your group-mates from English into Russian.

d) Give a reverse translation of the summary (from Russian into English).

Translate the text “Laser Diodes. Theory of Operation” with a dictionary in writing and compare the operation of a semiconductor junction diode with that of a laser diode.

A laser diode, like many other semiconductor devices, is formed by doping a very thin layer on the surface of a crystal wafer. The crystal is doped to produce an n-type region and a p-type region, one above the other, resulting in a p-n junction, or diode.

Laser diodes form a subset of the larger classification of semiconductor p-n junction diodes. As with any semiconductor p-n junction diode, forward electrical bias causes the two species of charge carrier – holes and electrons – to be "injected" from opposite sides of the p-n junction into the depletion region, situated at its heart. Holes are injected from the p-doped, and electrons from the n-doped, semiconductor. (A depletion region devoid of any charge carriers is formed automatically and unavoidably as a result of the difference in chemical potential between n- and p-type semiconductors wherever they are in physical contact.)

As charge injection is a distinguishing feature of diode lasers as compared to all other lasers, diode lasers are traditionally and more formally called "injection lasers." When an electron and a hole are present in the same region, they may recombine or "annihilate" with the result being spontaneous emission — i.e., the electron may re-occupy the energy state of the hole, emitting a photon with energy equal to the difference between the electron and hole states involved. Spontaneous emission is necessary to initiate laser oscillation, but it is one among several sources of inefficiency once the laser is oscillating.

In Russian write a content-based summary of the text you have translated.

Make a reverse written translation (from Russian into English) of your summary.

Find more information about the operation of different devices and tell your group mates.

UNIT V