本論文研究不同半導體晶圓及半導體微結構所產生兆赫波輻射的強度變化。藉由半導體表面鍍上一層共軛高分子材料（DB-PPV）改變半導體的介面態密度及表面電場達到增強其兆赫輻射的強度。我們發現在半絕緣的砷化鎵（GaAs）晶圓表面鍍上一層DB-PPV共軛高分子材料其兆赫輻射的強度增強55%。在N型摻雜及P型摻雜的砷化鎵晶圓上鍍上高分子材料後，其兆赫輻射的強度分別增強了31%及20%。至於在P型摻雜砷化銦（InAs）及銻化銦晶圓表面鍍上高分子材料後，其兆赫輻射強度並未增加。為了探討兆赫輻射強度增強的機制，我們量測在砷化鎵表面本徵－N+摻雜（SIN+）結構的表面鍍上高分子材料後介面態密度、表面電場及兆赫輻射強度等的變化，發現介面態密度、表面電場及兆赫輻射強度皆有百分之五（5%）的增加。因此我們推論表面電場的增加是促使兆赫輻射增強的原因。由於砷化鎵、磷化銦等半導體的表面電流主要為飄移電流，鍍上高分子材料後，其表面電場強度增加，增強其瞬間飄移電流的強度變化，使其兆赫輻射強度大大地增強。至於砷化銦及銻化銦等的表面光電流，主要為擴散電流，受到雷射脈衝激發後所產生的瞬時擴散電流的變化，為產生兆赫輻射的主因，但擴散電流並未受到表面電場變化的影響，因此在其表面鍍上共軛高分子材料雖亦可使其表面電場增強，但其兆赫輻射的強度則未改變。本研究中我們利用非接觸性、非破壞性的光調制光譜量測半導體微結構的表面電場變化來驗證以上的結論。

The THz radiation from various semiconductor wafers and microstructures is studied. Changes in surface field and the density of surface states are detected associated with the enhancement of the intensity of THz radiation by DB-PPV conjugate polymer surface-coating. The THz intensity of SI GaAs is enhanced by 50% by depositing the DB-PPV on its surface. For the semiconductors in which drift current dominates the diffusion current, THz radiation is enhanced by coating DB-PPV on their surfaces to increase their surface fields. For the semiconductors in which the diffusion current dominates the drift current, THz radiation is not enhanced by increasing in surface fields. The contactless and nondestructive modulation spectroscopy of photoreflectance is employed to determine the changes in surface field and the density of surface states which are closely related to the enhancement of the intensity of THz radiation.

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