d. Cic hing so quang
1.7.2. Cic exciton lien ket
Cac muc ning lugng electron rdi rac trong viing cam cua ZnO dugc sinh ra do cic tap chit hoac sai hdng trong vat lieu ban din, nd anh hudng din cic qui trinh hip thy va phat xa quang hpc. Kiiu vi cau tnic vimg cua vat lieu bin din inh hudng tdi cic trang thii electron cua liin kit exciton. Cac donor va acceptor trung hda ho$c tich difn
cd thi lien kit vdi exciton.
Cac lien kit donor - exciton (DBE) trung hda, ndng ndi chung chiim uu thi trong quang phd PL nhiet dp thap cua mang ZnO chat lugng cao do su cd mit cua cic nguln
liin kit acceptor - exciton (ABE) thinh thoang cung quan sit thIy d mpt vii mang ZnO cd ndng dp acceptor dang kị Cic vach sic net trong quang phd PL sinh ra do sy kit hgp cua cic exciton liin kit li diu hif u diing di nhan ra cic sai hdng hoic cic nguon tap chat khic nhaụ Mpi vach liin kit donor - exciton va acceptor - exciton diu quan sat dugc trong dai tii 3,348 - 3,374eV. Hinh ve 1.18 thi hifn quang phd PL cua mlu khdi ZnO, cic vach phd ndi bat do liin kit exciton A vi cic donor trung hda quan sit thIy d 3,3598 ( D X ) ; 3,3605 (D^XJ; 3,3618 (D?XJ; 3,3650 ( D X ) va 3,3664eV (DjX^ ). Vach phd manh khac quan sit thay tai 3,3724eV (D^Xg) la do liin kit exciton ly do B va cic donor. Khoang ning lugng giira peak đ va peak chinh tai 3,3605 (D^X^) vio khoang I2meV phii hgp vdi ning lugng phan tich ciia cic vach exciton ty do A va B. 6 viing nang lugng thap ciia quang phd cic vach ABE ciing quan sit thIy tai 3,3564 (ẢX^); 3,3530 ( A X ) v a 3 , 3 4 8 I e V ( A X ) T r o n g viing ABE, peak chinh tai 3,3564 (ÂX^) ndi chung ludn quan sat thay theo thdng bio cua cic nhdm nghiin curu khic nhau va cd thi cd liin quan din cic acceptor Na hoic Lị Hai peak yiu hon cd thi chi ra su cd mat ciia cic trang thii acceptor sau hon.
I
a
I ( D * X * )