3. V + P(B) —> E ~ K^.Np(NB) ~ ^p
4. V + Be mat —> Gay " hi-s
Trong do N^-. N02. Np(NB), K^ l a nong do v ac a nx i , nong do oxy, nong do t a p Photpho (Bo), nong do cac nguyen tii be mat tiiong ung. Ma
Ny = gOy vol g l a xac s u a t t a o vacanxị t y l e voi thong liiong (p, Cy l a
t h o i g i a n song cua vacanxị
Kill chj.eu xa lam x u a t h i e n s a i hong dan den t h a i g i a n song cua h a t t a i giam v i ;
Cj = C o / [ l + (KNi/No)] (3.3)
t r o n g do CQ, CJ l a t h a i g i a n song t n i o c v a sau Khi chiéu xạ KN^ l a tharih phan t y l e vol l i e u lutong c h i e u xạ -
Viee giam C dan den t h a y doi thong so ciia lirih l ^ e n nhur da t h a y
o t r e n . Sut hirih tharih tam t a i hcrp Khi b i chieu xa o mien emito lam cho
dac t n i n g V-A Khac v a i mien c o l e e t o v i mien nay ptia t a p cao hoTị Tam
t a i hop t r o n g mien day sau c h i e u xa lam cho t h a i g i a n t i e u hao Pban tii t a i d i i n Khong co ban p t o n t ^ emito sang ririarih hon. 6an den t h a i g i a n
t r e giam d i .
Dói VOI f o t o d i o t . do S i - n pna tap thap (10 ^"^ c m " ^ ché t a o
bang r^iutong phap epitajLi nen Khong co 6:^' v i vay chi co Khi nang t a o
- 42
t h a i g i a n g i a i phong d i e n tii Khoi bay tang dan den quan t i r i h tang. Tom l a i , v i e e hirih thanh cac tam sau do c h i e u xa gama t r e n cac l i i i h Kien ban rfan da lam t h a y doi n m e u dac t n i n g cua chung, Viee sii dung cae phep do t r e n vao nghien eutu l a chaia day d a Piiuang phap huu h i e u <^^ nghien eutu tam sau l a phiiong phap DLTS. Dieu do d a t cho chung
t o i rihiem vu xay dung h a i h e do DLTS dung d i e n dung v a dong qua dọ
$2-XAY IXJNG HE DO DLTS DUNG DIEN DUNG TMX) KY THUAT BOXCAR KEP 2. 1-Nguyen ly do
Xet t n i o n g hop tam b a t d i e n tut t r o n g ban dan N cua cau t n i c P -K , tut cac phiiong t r i r i h (1. 9)i (1. 15) t a co:
C(t) = Cf - C i e x p ( - e n t )
®n = SOn^n N c e x p ( - ( E c - ^ ) / K T )
Neu rihii Khong quan tam c^n tharih phan Khong doi Cf v a d^ y r ^ i g
1/2 3/2 , , ,
•^n"' T , Nc~ T , ô xem rihii Khong doi t h e o rihiit do tJni co t h e v i e t
(1. 9), (1. 15) o dang:
C ( t ) = C^exp (-êt) (3.4) 2
en = A- T erP(Br/KT) (3. 5)
O day CQ , A l a cac hang so nao do v o l A ~ ô va c o i day vung dan
EQ l a goe t o a dọ
Phutong t r i r i h b i e u d i e n cho t i m b a t l o tróng t r o n g ban d ^ P cua cau t n i c K -P hoan t o a n tiiong tii ( 3 . 4 ) , (3. 5) neu t h a y ê b ^ i g ep.
Cac thong t i n etui yeu can b i e t ve tam sau da ham chuta t r o n g (3. 4 ) , (3. 5) rihu: nang liiong i o n h o a Bp, tóc do p h a t xa d i e n t i i ệ t i e t d i e n b a t d i e n tii ( chuta t r o n g A) v a nong do tam Np ( chiia t r o n g CQ).
43 -
V ^ de l a Xii l y cac thong so do r a sao t r o n g cac h e do thiic nghiem Cac phufong t r i r i h ( 3 . 4 ) , (3. 5) cho t h a y dutong d i e n dung qua do phu thuoc vao h a i b i e n so: Nhlet do va I h a i gian.
C6 t h e b i e u d i m C = C ( t , T ) ( 3 . 6 )
Ftniong phap HJTS [64, 65] da diia r a Ky t h u a t xii l y t i n h i e u qua do
(3. 6) bang h e Boxcar Kep rihii sau:
T i n h i e u d i e n dung qua do diioc dbia vao n o t bo xut l y ma c h i t a i
h a i t h o i diem t j v a t ^ t i n h i e u moi diioc ghi rihan v a diia r a 6 l o i
r a cua bo xut l y nay h a i g i a t r i Cit^) v a C(t2) diioc diia vao bo
Khuyech d a i v i s a i . Loi r a cua bo Khuyech d a i v i s a i cho d i e n ap utng v o i dang dutcng qua do va v i t r i cua h a i cong t j va t g .
Hirih 3. 5 mo t a cac qua t r i r i h n o i t r e n .
C(t)
C ( t i )
C(t2)
^2 Thai gian
'L t ^- ^ ^^ -i- ^ •* v>
Hirih 3. 5 -Xii l y t i n h i i u qua do bang Boxcar Kep
Sau cau do d i e n dung t a rihin diioc t i n h i e u (3.4)
C ( t ) r C^exP ( - e n t )
- 44 Tf Tf f R(t) = I C(t) F(t) dt (3. 7) J O
O day Tf l a chu Ky l a p l a i ciia xung Kich m&u F ( t ) l a ham loc, dkc t n i n g cho tiing he xii lỵ
Vol h e Boxcar Kep, ham l o c co dang;
F ( t ) = a ( t - t i ) - a ( t - t 2 ) (3.6) t r o n g do d l a ham Dirac. Vol d i i u K l i n Tf > t j , t g , (3.7) t r o tharih: Tf f R(t) = I C ( t ) [ e ( t - t ) - d ( t - t )] dt (3.9) ' 1 2 J 0
O l o i r a cua h e Boxcar, t a rihin d i o c :
R ( t ) = C ( t i - C(t2) (3. 10) Do (3.4) CO t h e V i e t dbloc: R ( t ) = C e x p ( - e t ) - e x p ( - e 2) (3. 11) o ' n 1 n ' L I f^ , y
Do (3. 5) t a thay toe do phat xa dien tii en Phu thuoc rihiet do en = en(T )
- 45
Neu t i e n harih do R t2ieo sut thay doi rihiet do cua mau (thay doi en) t h i R se di qua ciic t r i , thoa man dieu Kien: