Toshiba DP120F Service Manual page 273

3.3.2 Semiconductor Laser
(1) Principle of light emission
When voltage is applied to metal, the electrons which have a negative charge move through
the metal so that a current flows through it.
With a semiconductor, the electrons with a negative charge and positive holes move in
the opposite direction through the semiconductor so that a current flows.
The positive holes, with their positive load, may be regarded as the "skin" that is cast off
after the transfer of electrons into the semiconductor.
March 2000 © TOSHIBA TEC
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Fig. 5-3-6
5-13 DP120F/DP125F Mechanical Description
05-03-05
05-03-06