Text b Joining p- and n-Type Germanium

Like N-type germanium, P-type germanium is also electrically neutral (Fig. 1).

When N-type germanium and P-type germanium are joined some electrons and holes combine at the junction. In the region of the junction, N-type germanium loses some of its electrons. Thus, it is no longer neutral in this area; it now has a positive charge. The electrons it loses, combine with holes

from P-type germanium at the junction. The P-type germanium becomes negative. The majority carriers have combined at the junction, leaving charged atoms (ions) in the area near the junction. A potential difference (of the order of several tenths of a volt) exists between the N- and P-type germanium ions. If more electrons try to move from the N-type to the P-type, they are stopped by the negatively charged ions in the P-type germanium near the junction (Fig. 2). In a similar fashion holes from the P-type are prevented from crossing the junction by the building up of positively charged ions in the N-type germanium. The net effect of this action is to set up a barrier voltage that prevents further combination of electrons and holes. The area in which this voltage exists is called the barrier region.

Fig. 1 Doped germanium is electrically neutral

Fig. 2 Electrons are stopped near the junction

22. Make a summary in Russian of the text you haven’t read.

23. Serve as a simultaneous interpreter of the summary stated above. Unit III

THE FORWARD-BIASED P-N JUNCTION

Language Work Forms of Participles

	Active	Passive
Present (I)	examining	being examined
Past (II)	--------	examined
Perfect	having examined	having been examined

For example:

• Speaking about the new method the engineer told us many interesting things.

• The results obtained are very important.

• Having been made carelessly the experiment proved useless.

Study the examples. When do the actions expressed by participles take place?

Predicative Constructions with Participles The Objective Participial Construction

1. Noun (Common case)/Pronoun (Objective case) + Participle I/II (after: feel, hear, notice, observe, perceive, see, watch, listen, have, get, imagine, help, etc.)

For example:

• We saw him providing an experiment.

• Please, help me to start these mechanisms working.

2. Noun (Common case)/Pronoun (Objective case) + Participle II (after: make, get, like, want, etc.) and when the subject represents a lifeless thing.

For example:

• He had the battery connected across the crystal.

• They wanted the holes removed from the positive end of the battery.

The Subjective Participial Construction (A Predicate is in Passive)

For example:

• He was seen providing the experiment.

• The electrons were noticed repelling from the negative end of the crystal.

• The current was perceived increasing very rapidly.