Thermally stable ohmic contacts to p-type GaAs. IX. NiInW and NiIn(Mn)W contact metals

Abstract

Thermally stable, low-resistance p-type ohmic contacts have been developed by depositing NiInW metals on GaAs substrates in which Be and F were coimplanted. The contacts provided resistances of about 1.4 Ω mm after annealing at temperatures in the range of 300–800 °C for short times. The electrical properties did not deteriorate after annealing at 400 °C for more than 100 h, which far exceeds the requirements for current GaAs device fabrication. The present study demonstrated for the first time that thermally stable, low-resistance ohmic contacts to both n- and p-type GaAs can be fabricated using the same metallurgy. In addition, NiInW ohmic contacts were prepared by simultaneous (one-step) annealing for ion-implant activation and contact formation, which simplifies significantly the device fabrication process. A factor-of-2 reduction of the contact resistances was achieved by slight etching of the GaAs surface prior to the contact metal deposition so that the metal/GaAs interface contacted the peak position of the Be concentration in the GaAs substrate. Another method used to reduce the contact resistance was to add a small amount of Mn to the NiInW metals: the resistance decreased with increasing amounts of Mn. The contacts had smooth morphology and shallow depth, less than 70 nm, which is desirable for very-large-scale integration device application.

Schottky barrier heights of contact metals to p-type ZnSe

“…Figure 6 shows measured ρ c values (indicated by open marks) reported for p-Si, 17 p-diamond, 10 p-GaAs, 18 and p-InP. Figure 6 shows measured ρ c values (indicated by open marks) reported for p-Si, 17 p-diamond, 10 p-GaAs, 18 and p-InP.…”

Ohmic contact to p-type GaAs using Cu3Ge

“…The NiInW system has been shown to form an ohmic contact to n-type (ϳ3ϫ10 18 cm Ϫ3 ) GaAs with a specific contact resistivity of 3ϫ10 Ϫ6 ⍀ cm 2 , and with the addition of Mn form an ohmic contact to p-type (ϳ2ϫ10 19 cm Ϫ3 ) GaAs with c ϭ1ϫ10 Ϫ5 ⍀ cm 2 . 7 Roedel et al 8 used an Al/Sn/Ni scheme to form ohmic contacts to both n-and p-type GaAs. The specific contact resistivities achieved with this contact scheme were 1ϫ10 Ϫ4 ⍀ cm 2 on n-type (ϳ3ϫ10 18 cm Ϫ3 ) GaAs and 5ϫ10 Ϫ4 ⍀ cm 2 on p-type (ϳ3ϫ10 19 cm Ϫ3 ) GaAs.…”