1. Fabrication Steps of Detectors
Etching Process
Thermal Evaporation Process for Indium
Diffusion Process
Spread Boron Powder over Ge Wafers
Assembly Process
Deposition of Electrodes
Removal of Excess Dopant Materials from the Surface of the Sampels

2. 1) Etching Process
Wet chemical etching is used for both germanium and cadmium telluride materials.
Material
Etching solution
Germanium
H2O:H2O2
(9:1)
Cadmium Telluride
HNO3:H3PO4:H2O
(1:70:29)

3. Before Ge CdTe
After

4. 2)Thermal Evaporation Process
■ Indium as a dopant material was deposited on the surface of (Ge) and (CdTe) with thickness 100nm. ■ Aluminium with thickness1μm was deposited on the other face of the samples for ohmic contacts. ■ This system can not work at temperature greater than 1000C°

5. 3) Diffusion Process Diffusion Ge CdTe Vacuum Environment
Water Environment
Nd:YAG laser λ=1064nm
Number of shots =10
Nd:YAG laser λ=1064nm
Number of shots =10
Nd:YAG laser λ=532nm
Number of shots = 8
Pulsed Energy
Pulsed Energy
Pulsed Energy 500 mJ
200 mJ
500 mJ
200 mJ
500 mJ
Indium diffused in Ge crystal with thermal evaporation process
Boron diffused in Ge crystal without thermal evaporation process
Indium diffused in CdTe crystal with thermal evaporation process

6. Diffusion process of CdTe in water environment

7. 4) Removal of Excess dopant materials from the surface of the samples
■Chemical method is used for removing the dopant materials (Indium,Boron).
■Chemical solution must have the following characteristics:
1)It should remove the dopant material from the surface of (Ge,CdTe) with high efficiency and short time.
2)It must not contain any impurities which may diffused in (Ge,CdTe).
Indium
HNO3:H2O (1:1)
H2O2
Boron
H2O

8. 5) Deposition of Electrodes
Aluminium Mask
Deposited Aluminium
Indium layer
Front side
Back side

9. 6) Assembly process
After cutting germanium and cadmium telluride to small pieces, each piece was fixed on a slide of glass and connected with copper wires .