本文關(guān)鍵詞： 金屬有機化學(xué)氣相沉積 原位沉積SiN_x插入層 位錯密度 GaN類金字塔狀微米錐　出處：《太原理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：GaN基半導(dǎo)體材料由于具有較高的禁帶寬度,優(yōu)良的物理與化學(xué)性質(zhì),已廣泛應(yīng)用于發(fā)光二極管,場效應(yīng)晶體管、大功率激光器和太陽能電池等領(lǐng)域。然而由于GaN材料與藍寶石襯底之間的晶格失配與熱失配,所生長的GaN材料位錯密度高,從而嚴(yán)重影響了其晶體質(zhì)量和光電性能。本論文主要針對如何改善GaN晶體質(zhì)量及形貌,采用金屬有機化學(xué)氣相沉積(MOCVD)方法原位沉積SiN_x插入層,分別制備了高質(zhì)量的GaN外延薄膜及形貌可控的類金字塔狀GaN微米結(jié)構(gòu),系統(tǒng)研究了SiN_x插入層沉積時間、沉積位置及不同生長模式對GaN外延薄膜晶體質(zhì)量影響;同時研究了生長溫度、生長時間、反應(yīng)壓力和Ⅴ/Ⅲ比等不同生長參數(shù)及KOH溶液腐蝕對類金字塔狀GaN微米結(jié)構(gòu)形貌的影響,并對其機理進行了探討。具體的研究結(jié)果如下:通過MOCVD在原位沉積的SiN_x插入層上生長了GaN外延薄膜。原位沉積SiN_x插入層能降低Ga N薄膜的位錯密度,提高電子遷移率及GaN薄膜質(zhì)量;SiN_x沉積時間為120 s時,在其上生長的GaN薄膜的晶體質(zhì)量高于SiN_x沉積時間為60 s及180s時生長的GaN薄膜;在沉積120 s SiN_x插入層后采用兩步法生長GaN薄膜會導(dǎo)致晶體質(zhì)量的變差,這是由于低溫下生長GaN形核層內(nèi)部重新出現(xiàn)大量位錯所致;在退火后的形核層上沉積SiN_x插入層后再生長的GaN薄膜位錯密度最低,晶體質(zhì)量最高,這是由于減少了GaN的形核位置所致。通過在MOCVD原位生長的SiN_x插入層上制備了形貌可控的類金字塔狀GaN微米結(jié)構(gòu)。當(dāng)生長溫度為1075℃時,所生長的GaN呈現(xiàn)出類金字塔狀微米錐形貌;當(dāng)生長時間由3 min增長至20 min時,微米錐的底面直徑由3.6μm增大到19.8μm,密度由3.8×10~3 cm~(-2)降至0.8×10~3 cm~（-2）;壓力及V/III比共同決定該結(jié)構(gòu)頂部的微觀形貌(錐狀或截頂錐狀)。KOH溶液會腐蝕類金字塔狀GaN微米錐的側(cè)壁,使其側(cè)壁呈現(xiàn)層狀分解,在腐蝕20 min后形成微米棒狀結(jié)構(gòu),其尺寸大小與微米錐頂部的形貌有關(guān)。
[Abstract]:GaN based semiconductor materials have been widely used in light emitting diodes and field effect transistors due to their high band gap and excellent physical and chemical properties. However, due to lattice mismatch and thermal mismatch between GaN materials and sapphire substrates, the dislocation density of grown GaN materials is high. Therefore, the crystal quality and optoelectronic properties are seriously affected. In this paper, we focus on how to improve the quality and morphology of GaN crystal. High quality GaN epitaxial films and pyramidal GaN microstructures with controllable morphologies were prepared by in-situ deposition of SiN_x inserts by metal-organic chemical vapor deposition (MOCVD). The effects of deposition time, deposition location and different growth modes of SiN_x on the crystal quality of GaN epitaxial films were systematically studied. The effects of growth temperature, growth time, reaction pressure, V / 鈪，

本文編號：1473173