本研究利用不同參數之反向式濺鍍蝕刻法(inverse sputter etching
technique)轟擊半導體材料表面以去除潛在的表面汙染物，如天然氧
化物與碳氫化合物，使其半導體-金屬接面之接觸電阻最小化。並利
用濺鍍方式沉積鉻/金雙層金屬，製作出具有良好歐姆接觸之雙電極
半導體元件。在氧化亞銅(Cu2O)方面，以濺鍍方式製作氧化亞銅(111)
及(200)面單晶塊材與(100)面磊晶薄膜元件，並探討其電傳輸及光電
導特性。使用熱探針法確認此氧化亞銅為P 型半導體。氧化亞銅單晶
塊材與磊晶薄膜之電導率約為10-3 S/cm。變溫暗電導量測顯示，不同
晶面方向之氧化亞銅，其主要載子可能皆來自不同的來源。以532 nm
波長的綠光雷射進行光電導量測，計算出單晶塊材與磊晶薄膜之歸一
化增益值分別約為10-5 ~10-4 cm2V-1 與10-8 cm2V-1。此外，本研究建立
一物理模型解釋氧化亞銅單晶塊材與磊晶薄膜在綠光雷射下之載子
活期行為與近紫外光雷射之光電流變化情形。由此模型可以推測，氧
化亞銅之表面缺陷與空氣中的氧或水分子可能有明顯的交互作用。

In this study, the technique of inverse sputter etching has been used to
minimize contact resistance in the metal-semiconductor interfaces by
removing the potential surface contaminants such as native oxides and
hydrocarbons. Two-terminal devices using Cr/Au bi-layer contact
electrodes with great ohmic contact condition have been achieved. For
the study of cuprous oxide (Cu2O), the devices of Cu2O (111) and (200)
single crystals and Cu2O (100) epitaxial films have been fabricated by
sputter, and the electronic transport properties and photoconductivities in
Cu2O have been investigated. Hot-probe method confirmed that the Cu2O
single crystal is a p-type semiconductor. The conductivities of Cu2O
single crystals and an epitaxial film are around 10-3 S/cm.
Temperature-dependent conductivity measurement shows that the
majority carriers in the Cu2O with different out-of-plane orientations
could be activated from different defect levels or defect bands.
Photoconductivities in Cu2O by the excitation of the wavelength of 532
nm were also investigated. The normalized gain of the Cu2O single
crystals and the epitaxial films are 10-5 ~10-4 cm2V-1 and 10-8 cm2V-1,
respectively. In addition, a physical model based on the p-type
semiconductors has been proposed to explain the carrier lifetime under
532 nm green laser excitation and an anomalous photoresponse curve
under 325 nm UV illumination. It is inferred that the surface defects in
Cu2O exhibit strong interaction with the ambient molecules such as
oxygen and water.
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