2h^s 2^2 la nang lupng lien ket cua exciton.
1.6, Tdng quan ve dung dich ran Zn^Cd^xS
dung dung dich ran ban din ZnxCdị^S.
Dl nhan dupe dung dich rin ban din Zn^Cdj.^S ngudi ta thudng dung phuang
phap keo dan tinh thi trong khf tra [12,7], phuang phap ling dpng tut pha hoi [87], phuang phap phun dung dich len de ndng [70,47,83], hoac bdc bay nd [13].
Cac tic gia [71] da suf dung miu ZnxCd|.xS d dang bpt dl nghien ciiu quang huynh quang. Tap chit Cu cung dupe trdn vao miu bdt dudi dang dung dich long Cu(C2H30).
Cac tie gia [37] ciing nghien ciiu dien huynh quang cua miu Zn^Cdị^S d dang bpt: bpt ZnS va CdS trdn ciing mudi tap chat Mn va Sn rdi nung trong khi H2S d 900''C trong 2 gid.
Dd rdng vung cam cua ZUxCdj.^S dupe cac tic gia [7] khao sat tai nhiet dp 77 K, Eg thay đi tii 3,84 eV khi x = 1 den 2,58 eV khi x = 0. Ddng thdi dien trd suit cua cac tinh the nay ciing thay đi tu p = 10^ Q.cm khi x = 1 den p = 10^^ Q.cm
khi X = 0. Cac tac gia [13] da nghien ciiu su thay đi theo thanh phan x cua dp rdng viing cim va tinh chat huynh quang cua mang Zn^Cdi^^S ch^ tao bang phuong phap bdc bay nd. Tfnh chat huynh quang cua da tinh the Zn^Cdj.xS che tao trong khi tra
da dupe cac tic gia [12] nghien ciiụ Su phu thupc vao nhiet đ de cua he sd truyen qua va đ din dien cac mang Zno,2Cdo,8S ch^ tao bing phuang phap phun dung dich dupe nghien ciiu trong [83]. Cac tie gia [32] da nghien ciiu su md rpng ciia phd phan xa exciton ciia tinh thi ZnxCdị^S.
Ngoai cac nghidn ciiu ca ban, cic tic gii [47,70,48] da nghien ciiu che tao cic
chuyin tiep di thi de ling dung lam pin mat trdị Chuyin tiep di thi dupe quan tam
nhi^u nhit va cd ling dung nhi^u nhat la CUxS/CdyZuịyS. Viec suf dung dung dich
rin Zn^CdịxS cho phep lam tang the hd mach, nhung lai Iam giam đng doan match
cd 6% a difeu kien mat đ biic xa 130 mW/cm [8]. Cac laze bin din su dung
Zno,o9Cdo3iS dupe che tao va boat đng tdt trong mi^n 4,2 - 360K. Tai 4,2K budc
sdng laze la 0,431pm, tai 120K la 0,437|im. Cic photodiot, cic quang trd Zn^Cdị^S dupe che tao bing cac phuang phap bdc bay, phun dung dich da dupe mot sd tic gii nghien ciiu ling dung [58,8].
Tom lai nhieu tic gia da nghien ciiu dung dich ran ban din Zn^CdịxS d dang bdt, tinh the va mang. Cac hudng nghidn ciiu chii ydu la tinh chat dien, tfnh chit quang, huynh quang va cac chuyen ti^p di the tren dung dich rin Zn^Cdj.^S. Cac cdng trinh nghien ciiu huynh quang đu tap trung vao nghien ciiu ZnxCdị^S d dang bpt [71,37] hoac mang chl^ tao bing phuang phap bdc bay nd [13] hay da tinh the [12]. Cac mang ZnxCdj.^S ch^ tao bang phuang phap phun dung dich phan Idn chi dupe nghien ciiu ve cac tinh chit dien va ling dung de lam cac linh kien quang dien.
1.7. Ket luan
Tren day, chiing tdi trinh bay mot cich vin tit nhiing dac trung ca ban, nhiing
ca sd ly thuyet, torn tat cac ket qua nghien ciiu khac nhau ve hop chit ban din ZnS,
CdS va dung dich rin bin dan tren ca sd cac hop chat iỵ Mac du cd rit nhfeu ket qua xung quanh linh vuc nay nhung vin con nhieu diem cin dupe nghien ciiu, ban
luan tiep tuc:
- Tinh chat quang, huynh quang cua dung dich ran ban din Zn^Cdj.xS mdi chi dupe nghien ciiu tren miu bdt, mau dupe che tao bang phuang phap bdc bay trong
chin khdng, bdc bay nd; con cac mang tao bang phuang phap phun dung dich thi
chua dupe nghien ciiụ Tuy ring cung la dung dich ran Zn^Cdj.xS nhimg phuang
phip tao miu khac nhau cd the gay anh hudng khac nhau den su hinh thanh cic tam huynh quang trong maụ Dd la ly do tai sao chiing tdi chpn phuong phap nay de tao
mang Zn^Cdj.xS cho nghien cuu tinh chit quang va huynh quang.
- Ciing vi muc dich la nghien ciiu huynh quang cho nen dan tim ra chef dp tao miu tdi uu cho tfnh chat huynh quang. Va lai, d mdi he cu the ch^ đ tdi uu cd thi
khic nhaụ
- Kha nang tii hop biic xa dono - axepto chua dupe mot tic gia nao de cap d^n
đi vdi dung dich rin ban din ZnxCdị^S. Ca che huynh quang se dupe lam sang to hon n^u ngoai cic phd huynh quang ta khao sat them cac phd huynh quang phan giai thdi gian, thdi gian sdng huynh quang, su phu thupc ciia phd huynh quang vao
cudng dp kich thich.
- Md hinh tam tap chat trong mang Zn^CdịxS va vai trd cua tam tap ay trong ca che phat huynh quang chua dupe cac nha nghien ciiu phin xet mot each day diị
Chuong 2. KY THUAT THl/C NGHIEM
Tren ca sd mdt sd thil^t bi va he nghien ciiu sin cd d bp mon, trong qua trinh
lam luan an chiing tdi da bd sung cac thiet bi mdi, cii tao cic he cu dl xay dung cac he nham chef tao mang va do cac phd hip thu va quang huynh quang cua cac mang
ZnxCdi,xS. 2.1. He tao mang 8 10 k 11 12 tKHsawgffljriiiwaiâ^^iâíaÊ^i^j^ 13
Hinh 17. Sd đ he tao mang
1-L6
2 - Ong thach anh 3 - Ga miu
4 - M6ta quay miu 5 - Cap nhiet dien
6-Bil'nth^tungiu 7 - May do nhiet dp 8 - Bp khóng chi nhiet dp 9 - Ong dung dung dich
10 - V6i phun dung dich
11-Voi thdi khi 12-Luu lupng k^ 13 - May nen
Cac mang ZUxCdj.xS dupe ché tao tai phdng thf nghiem cua bd mdn Vat ly Dai cuang, bang phuang phap phun dung dich len dé ndng. Vdi mdt sd thiet bi mdi nhu may nen, tii hiit, md to quay, he thdng ga do, vdi phun, ga miu va bp khdng che nhiet dp, may do nhiet dp, chiing tdi da xay dung iai he phun mang. So do he ché
tao mang dupe trinh bay tren hinh 17.
2.1.1 Lo
Ld hinh tru, dupe dat tren gia sit. Vd Id iam bang nhdm, lap each nhiet ia bong amiang day 10 cm. Budng phun la dng thach anh cl> = 10 cm, dai 50 cm. Day dien trd vdi dien trd suit la p = 5 Q.cm dupe quin true tiep len dng thach anJị
Nhiet dp id dupe on dinh nhd bp khdng ché nhiet dp TH-22. Bp khdng che cho phep dat ttxrdc nhiet dp T can thiet. Nhiet dp de miu Td trong qua trinh phun dupe do bang may do hien sd M50, thdng qua cap nhiet dien Alum.en-Chromel.
2.1.2 Bo ga mau
Di giii miu trong budng phun, chiing toi sir dung bp ga miu bang thep khdng
rị Bp ga cd 4 ngan nim tren ciing mdt mat phing vudng gdc vdi hudng phun ciia dung dich. Trong mdi ngan cd the dat mot de, do đ ciing mpt liic cd the phun dupe
4 mang. Bp ga dupe gin vao mdt thanh thep khdng rị Thanh nay dupe ndi vdi mdta
quaỵ Nhd mdta quay nay, toan bo bp gi miu dupe quay trdn trong budng phun. Tdc đ quay cua bp ga miu cd the ididng che bdi ngudn dien nudị Thong thudng
khi đng dien qua mdta ca 0,9 A thi tdc dp quay dat dupe ia 40 vdng/'phiit. Neu
quay nhanh qua mang se diy ban d phan gan tam thanh quay, d phfa xa tam mang
se mong. Néu quay cham qua, mat mang khdng đng deu, mang khdng bam chat vao lamen, dl bi bong rạ