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本研究之研究目的旨在探討國內上市公司進行撤資活動對其股價與未來營運績效所產生的影響。研究期間為民國八十年一月一日至八十六年十二月三十一日，經搜集相關資料後共取得57個符合條件的撤資樣本。本研究以撤資宣告日前31日至宣告日前120日為市場模式之估計期，而以撤資宣告日前300日至宣告日後30日為事件觀察期，採用事件研究法分析撤資賣方公司的撤資宣告效果。除此之外，本研究亦以五日累積異常報酬為依變數，而以公司規模、撤資規模、撤資損益、公司財務狀況、股票市場多空為自變數進行橫斷面複迴歸分析，試圖找出影響累積異常報酬的因素，最後並利用簡單迴歸模型進一步比較公司撤資前後之營運績效是否有顯著差異，經由實證分析後得到以下研究結論： 一、撤資宣告對公司股價的變動具有顯著正面的影響，股東在公司宣告撤資期間可享有超額報酬。 二、我國上市公司在宣告撤資時，其撤資相對處分損益對股價的撤資宣告效果具有顯著正面的影響；至於撤資交易的規模大小則對股價的撤資宣告效果沒有顯著的影響。 三、我國上市公司在宣告撤資時，其撤資後有無清償債務對於股價的撤資宣告效果會有不同的影響。 四、公司進行撤資對其未來的營運績效沒有顯著正面的影響。顯示公司在進行撤資後，其營運績效沒有獲得大幅地改善。 最後，本研究以研究結論，分別針對政府、企業界、投資者及後續研究者提出一些建議，期盼這些建議能夠對於其從事相關決策、學術研究時有所助益。

This work describes multiband photon detection techniques based on novel semiconductor device concepts and detector designs with simultaneous detection of dierent wavelength radiation such as UV and IR. One aim of this investigation is to examine UV and IR detection concepts with a view to resolve some of the issues of existing IR detectors such as high dark current, non uniformity, and low operating temperature and to avoid having additional optical components such as filters in multiband detection. Structures were fabricated to demonstrate the UV and IR detection concepts and determine detector parameters: (i) UV/IR detection based on GaN/AlGaN heterostructures, (ii) Optical characterization of p-type InP thin films were carried out with the idea of developing InP based detectors, (iii) Intervalence band transitions in InGaAsP/InP heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. Device concepts, detector structures, and experimental results are discussed. In order to reduce reflection, TiO2 and SiO2 nanostructured thin film characterization and application of these as anti-reflection coatings on above mentioned detectors is also discussed.

This work describes infrared (IR) photon detector techniques based on novel semiconductor device concepts and detector designs. The aim of the investigation was to examine alternative IR detection concepts with a view to resolve some of the issues of existing IR detectors such as operating temperature and response range. Systems were fabricated to demonstrate the following IR detection concepts and determine detector parameters: (i) Near-infrared (NIR) detection based on dye-sensitization of nanostructured semiconductors, (ii) Displacement currents in semiconductor quantum dots (QDs) embedded dielectric media, (iii) Split-off band transitions in GaAs/AlGaAs heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. A far-infrared detector based on GaSb homojunction interfacial workfunction internal photoemission (HIWIP) structure is also discussed. Device concepts, detector structures, and experimental results discussed in the text are summarized below. Dye-sensitized (DS) detector structures consisting of n-TiO2/Dye/p-CuSCN heterostructures with several IR-sensitive dyes showed response peaks at 808, 812, 858, 866, 876, and 1056 nm at room temperature. The peak specific detectivity (D*) was 9.5E+10 Jones at 812 nm at room temperature. Radiation induced carrier generation alters the electronic polarizability of QDs provided the quenching of excitation is suppressed by separation of the QDs. A device constructed to illustrate this concept by embedding PbS QDs in paraffin wax showed a peak D* of 3E+8 Jones at ~540 nm at ambient temperature. A typical HEIWIP/HIWIP detector structures consist of single (or multiple) period(s) of doped emitter(s) and undoped barrier(s) which are sandwiched between two highly doped contact layers. A p-GaAs/AlGaAs HEIWIP structure showed enhanced absorption in NIR range due to heavy/light-hole band to split-off band transitions and leading to the development of GaAs based uncooled sensors for IR detection in the 2 5 μm wavelength range with a peak D* of 6.8E+5 Jones. A HIWIP detector based on p-GaSb/GaSb showed a free carrier response threshold wavelength at 97 µm (~3 THz)with a peak D* of 5.7E+11 Jones at 36 μm and 4.9 K. In this detector, a bolometric type response in the 97 - 200 µm (3-1.5 THz) range was also observed.