四针状氧化锌晶须的生长机理

Growth mechanism of tetrapod ZnO whiskers

用“时间标尺”实验法测定了T ZnO晶须在不同生长时期的生长速率, 用扫描电镜观察分析了不同条件下晶须的生长形貌。结果表明: T ZnO晶须的结晶作用是气 液 固(VLS)方式, 晶须生长受螺旋生长机理控制; 锌蒸气中产生凝聚生长的锌液滴是制备T ZnO晶须的关键, 锌从液滴内向外扩散在晶须的端面产生生长台阶, 随着液滴内的原子向外不断扩散, 针体部分就不断地伸长生长, 当液滴内的原子全部消耗尽时, 晶须便不再发生轴向生长; 气 固(VS)方式的作用主要是促进晶须棱面生长而使晶须变粗, 对轴向生长几乎没有影响。

The growth rate at different growth stages of tetrapod ZnO was determined by the “time mark” experiments and the morphologies formed under different conditions were examined by scanning electronic microscope. The results show that the growth rate of tetrapod ZnO is controlled by spiral growth and its crystallization is via VLS model. The condensation of tiny zinc droplets in zinc vapor is the key factor of the formation of tetrapod ZnO. The growth steps are formed on the terminated faces as zinc diffuses outwards and the elongation of whiskers continues until zinc inside the droplets is depleted. VS crystallization, which has little effect on the elongation growth, takes place on side faces of the whiskers and consequently makes the whiskers radius increase.