快速升溫退火砷離子佈值砷化鎵光導開關之研究

Abstract

本論文主要探討不同劑量砷離子佈植砷化鎵薄膜材料在快速升溫退火製程之後所製作的光導元件的特性。 在暗電流方面，由於退火時間仍無法使大部分晶格恢復，接面呈現類似歐姆接觸，使得暗電流隨著佈值濃度增加而增加。時域響應量測方面，則利用光脈衝寬約150fs、波長為0.81um被動鎖模鈦藍寶石雷射為光源，在經過厚度為60um的電光晶體LiTaO3的外部電光取樣系統的量測之下：600℃、150秒的快速升溫退火製程使得1013ions/cm2劑量砷離子佈值砷化鎵製作的共面微條形光導開關(CPS)，具有約4.10ps的時域響應，而1014lons/cm2、1015ions/cm2、1016ions/cm2劑量的光導開關經量測之後也有約3.95ps、3.72ps及3.60ps的時域響應，上升時間則皆約為2ps。 綜合歸納四種佈植劑量的學導，我們發現經快速升溫退火600℃、150秒的1013ions/cm2的光導，擁有響應度高(0.016A/W)、暗電流低(4.6×10-5A)及響應時間與其他劑量樣品相去不遠的特點，我們認為以此劑量為材料的樣品，在四種劑量中具有較佳之特性。

We have studied the characteristics of photoconductiv switchs fabricated on rapid-thermal-annealled GaAs that were implanted with 200keV arsenic ions at different dosages. The dark currents of the devices were observed to be increasing with the implanting dosage. By using a passive-mode-locked Ti:Sapphire laser (λ=0.81 um) generating 150fs optical pulses, in an external electro-optic sampling system with a 60um electro-optic probe, we found the temporal response of devices fabricated with rapid-thermal-annealled GaAs implanted with 1013cm-2 arsenic ions to be 4.1ps full width at half naximum (FWHM) For samples implanted at 1014 cm-2, 1015 cm-2 and 1016cm-2, the responses are 3.95ps, 3.72ps, 3.60ps, respectively. The best performance was achieved with samples implanted at 1013cm-2 The devices exhibit a response of 0.016A/W, dark current of 4.6×10-5 A and response time comparable to those implanted at either lower or higher dosages.