In order to study its diffusion mechanism, Zn was diffused from a ZnAs2 source into Si-doped samples, at temperatures ranging from 575 to 700C, in sealed evacuated quartz tubes. The samples were characterized by means of the depth profile of the photoluminescence at various temperatures. The photoluminescence spectra contained characteristic emissions which were associated with deep levels of Ga and As vacancies. A detailed analysis of the spectra revealed the role that was played by vacancies in the Zn diffusion process. A spatial correlation between the luminescence spectra, and the Zn concentrations deduced from secondary ion mass spectrometric data, was demonstrated. It was found that the data (table 28) could be described by the expression:

D(cm2/s) = 2.05 exp[-2.28(eV)/kT]

N.H.Ky, L.Pavesi, D.Araujo, J.D.Ganière, F.K.Reinhart: Journal of Applied Physics, 1991, 69[11], 7585-93

 

Table 29

Diffusivity of Zn in GaAs

 

Protection

Source

Temperature (C)

D (cm2/s)

ZrO2

Zn

755

3.8 x 10-11

ZrO2

Zn

700

1.2 x 10-11

ZrO2

Zn

650

6.9 x 10-12

ZrO2

Zn

600

1.3 x 10-12

ZrO2

GaAs/Zn2As3

650

2.0 x 10-12

-

GaAs/Zn2As3

650

1.6 x 10-12

ZrO2

GaAs/Zn2As3

600

4.5 x 10-13

-

GaAs/Zn2As3

600

3.8 x 10-13

-

GaAs/Zn2As3

755

1.2 x 10-11

-

GaAs/Zn2As3

700

4.0 x 10-12

ZrO2

GaAs/Zn2As3

700

3.1 x 10-12

ZrO2

GaAs/Zn2As3

755

9.7 x 10-12