[????]????

¢ñ. ????? ??

????? ?? ??? ??? ??? ??? ?? ? ??. ???? ???? ??? ?????? ??? ??? ????? ??? ??? ??(solar thermal electricity)??, ???(photons)? ???? ??? ???? ?????? ????? ??? ??? ??(photovoltaic solar cells)??. ??? ??? ????? ?????? ????? ????? ?? ????(lighting emitting diode, LED)? ??? ????(laser diode)? ???? ???? ??. ????? ??? ??? ???? ?? ?? ???? ??? ???? ???? ???? ??? ? ??.
??? ??? ????? ???? p-n?? ????? ???? ??. ?? ??? ??? ?? ????? ????? ??? ?? ??? ??? ?? ??? ???? ?????? ???? ??? ???. ??1? p-n ??? ????? ??? ???.


(??-1) p-n??

n-type ??? ? ????(electron density)? ?? ????(hole density)? ??? ?? p-type ??? ?? ???? ????. ??? ?? ?????? p-type???? n-type???? ???? ???? ??????? ???(carrier)? ?? ??? ?? ???? ??(charge)? ???? ??? ? ??? ???(electric field)? ???? ? ?? ???? ??? ???? ?? ??. ? ????? ? ??? ???(conduction band)? ????(valence band) ??? ??? ??? ??? ??? ??? ?? ??? ??, ? ????? ??? ???? ?????? ???? ??(excite)??. ? ? ???? ??? ???? ???? ??? ? ?? ??, ?????? ???? ???? ??? ??? ????. ??? excess carrier?? ?? ? excess carrier?? ??? ?? ???? ??? ????? ??? ???? ??.
?? p-type????? ??? ???? n-type????? ???? ??? ??? minority carrier?? ???, ?? ?? ?? p-type ?? n-type????? carrier(p-type? ??, n-type? ??)? ?? ??? majority carrier?? ???. ? ? majority carrier?? ????? ?? energy barrier ??? ??? ??? ??? p-type? minority carrier? ??? n-type??? ?? ??? ? ??.