半極性氮化銦材料成長與分析

Growth and Characterization of Semi-Polar InN Materials

氮化銦為一直接能隙半導體，其能隙約為0.7 eV，適合應用於紅外光區之光電元件中，因沿c軸生長之極性InN具有較大的自發性極化效應，會降低電子電洞的複合機率，因此可利用半極性或非極性InN，增加光電效率。半極性InN之研究中，以鋁酸鑭（LaAlO3，LAO）（112）單晶做為基板，在不同溫度成長半極性InN（10¯13）薄膜。當半極性InN薄膜沉積在510°C時有最佳結晶性，其（10¯13）與（0002）半高寬分別約為1408與1830 arsec，且會有兩組180度對稱之晶域（Domain），其磊晶關係為（10¯13）InN //（112）LAO與[1¯210]InN // [11¯1]LAO。另外，LAO與InN之間有極低晶格不匹配率（[1¯210]InN方向約為-7.75%，[¯3032]InN方向約為0.2%），電性方面，半極性InN成長溫度於510°C有最高之電子遷移率與最低載子濃度。光學特性經由PL光譜在10 K量測結果顯示，NBE訊號範圍約為0.72至0.81 eV。在510°C所沉積之InN在所有的樣品中有最強的放射訊號與窄的半高寬值。因此，本研究主要在探討半極性InN生長於（112）鋁酸鑭（LaAlO3，LAO）單晶基板上時所呈現出不同的光電與顯微結構特性。藉由其展現之光電與顯微結構之特性與行為便瞭解薄膜成長機制，有助於提升InN-based磊晶薄膜之品質。 InN material is a direct energy gap semiconductor which is potential for optoelectronics and electronics application. Semipolar InN(10¯13) films were prepared on LaAlO3(112) substrate by varying the substrate temperature. The results show that semipolar InN(10¯13) layers can be grown at 510 °C with the(0002) FWHMs value of 1830 arcsec and(10¯13) XRC FWHMs value of 1408 arcsec. Also, the InN fi lm is in epitaxy with LAO substrate with orientation relationships of InN(10¯13) // LAO(112) and [1¯210]InN // [11¯1]LAO. The lattice mismatch between InN and LAO can then be estimated to be 7.75 % along the [1¯210]InN direction and 0.2 % along the [¯3032]InN direction. Electronic properties showed that the InN film grown at 510 °C exhibits the highest electron mobility of 494 cm2/V-s and lowest carrier concentration of 2.4×1019 cm-3. PL spectra at 10 K showed the peaks of near band-edge emission at energies between 0.72－0.81 eV. However, InN grown at 510 °C has the highest peak intensity and the narrowest FWHM of these samples which has better quality.