| 摘要: | 氧化鎵材料(Ga2O3)為新型寬能隙氧化物半導體，由於其適合做為高功率元件之材料性質，提高了在市場中的應用性與發展性，而為因應市場需求與降低成本，大尺寸的晶體需求亦逐漸提升，β-Ga2O3的優勢在可由液相生長，其中由於柴氏長晶法(Czochralski method, CZ)是目前常用來生長高品質單晶的方法之一，具有較佳的品質控制，而氧化鎵為半透明氧化物，在長晶過程中晶體會受到內部輻射的強烈影響。
透過本研究結果顯示，減少晶體吸收係數會影響晶體內部輻射特性，並影響晶體熱場分布，改善固液界面形狀，避免晶體呈螺旋狀生長，以獲得較佳的晶體品質。提高長晶過程之拉晶速率，固液界面會釋放更多固化潛能，降低軸向溫度梯度，使固液界面位置上升並降低界面凸出率，加熱器功率也會隨拉晶速率上升而下降。在晶身長度方面，隨著晶身長度越長，內部輻射效應越明顯，吸收係數較小時，界面會更凸向熔湯，因此界面凸出率會隨著晶身長度上升而增加；吸收係數較大時，界面會逐漸凹向熔湯，因此界面凸出率會隨著晶身長度上升而降低，由於物體遵守質量守恆，因此熔湯深度與溫差會降低使熔湯中心流速下降。
;Gallium oxide (Ga₂O₃) is a new wide bandgap oxide semiconductor, known for its properties suitable for high-power devices, enhancing its applicability and development potential in the market. To meet market demand and reduce costs, the need for large-sized crystals is gradually increasing. One of the advantages of β-Ga₂O₃ is that it can be grown from a liquid phase. The Czochralski method (CZ) is one of the most commonly used methods for growing high-quality single crystals, offering better quality control. However, as gallium oxide is a semi-transparent oxide, the crystal is strongly affected by internal radiation during the growth process.
The results of this study indicate that reducing the crystal absorption coefficient affects the internal radiation characteristics, which in turn influences the thermal field distribution within the crystal, improving the solid-liquid interface shape and preventing spiral growth, thus achieving better crystal quality. Increasing the pulling rate during the growth process releases more latent heat at the solid-liquid interface, reducing the axial temperature gradient, causing the interface position to rise, and lowering the convexity of the interface. The heater power also decreases as the pulling rate increases. Regarding the length of the crystal body, as the length increases, the internal radiation effect becomes more significant. When the absorption coefficient is smaller, the interface becomes more convex toward the melt, thus the convexity increases with the length of the crystal body. When the absorption coefficient is larger, the interface gradually becomes concave toward the melt, so the convexity decreases as the length of the crystal body increases. Due to mass conservation, the melt depth and temperature difference decrease, leading to a reduction in the flow rate at the center of the melt. |
