The diffusion length of minority carriers in P-Ga(1-x)In

x

As

y

P

1-y

(

x

=0.74

y

=0.61)grown on InP substrate were determined by measuring the photocurrent under laser scan ard electroluminescent decay of the LED.The carrier concentration of the P-Ga(1-x)In

x

As

y

P

1-y

epitaxial layer is 2×10

17

cm

3

while the layer thickness is 2~3nm.The photocurrent response R of the sample was measured as a function of distance(x)from the p-n junction(Fig.4)

using a He-Ne laser with a wavelength of 6328A as the scanning light source.R is expressed as a function of the diffusion lengths(Ln)

diffusion coefficients(Dn)

surface recombination velocities(S)and photoabsorption coefficients(α).Csee Equation(1)]The electroluminescent decay method is somewhat indirect.The diffusion length(L)of the minority carriers is determined through the relation L=(Dτ)1/2

in which D is the known diffusion coefficient ard τ is the decay time of luminescence.The light emitting diodes were prepared with the samples used in the laser scan experiment.It was assumed that trapping lifetime has little influence on electroluminescence decay time.Experimental results of the two methods are ccmtrred in Table 1.The results show good agreement.The two independent experiments were analyzed simultaneously to obtain surface recombination velocity S.S is 6~7×10

4

cm/s.Diffusion length L

is 1.6~2.2μm.Moreover

the behaviour of the minority carrier in P-Ga(1-x)In

x

As

y

P

1-y

on InP substrate were discussed.