Shallow and Thermally Stable Ohmic Contacts to p-InAsP

Abstract

We have investigated the electrical and metallurgical behavior of ohmic contacts to p-InAs 0.80 P 0.20 . Auger depth profiling reveals that Ru, Ti, and V have better thermal stability against reaction than Pt, Pd, and Ni on p-InAsP. However, contacts with Pd deposited as the first layer exhibit lower specific contact resistances than contacts with Ti, V, Ni, Ru, or Pt as the first layer. For this reason, multilayer contacts were studied, adding Au as the top layer to minimize the metal sheet resistance. Transmission electron microscopy indicates that Pd/Ru/Au contacts aged for 3 days exhibit a uniform and shallow reaction with p-InAsP, with the Pd consuming only 4 nm of the semiconductor and the Ru serving as an effective diffusion barrier. Specific contact resistances of 3.8 ϫ 10 −6 ⍀ cm 2 as deposited and 1.7 ϫ 10 −6 ⍀ cm 2 for contacts aged at 250°C for 90 days in an evacuated quartz tube were measured for the Pd/Ru/Au contacts.

High-Yield Growth and Characterization of ⟨100⟩ InP p–n Diode Nanowires

“…Ohmic contacts can be established on p-doped InAsP and InAs. 38,39 In the top segment of the nanowires, we measured by energy dispersive X-ray spectroscopy (EDS), a fraction of As in the NW increasing from 0 up to 0.56 ± 0.06, which is in good accordance to the molar fractions used. We limited the As content in order to achieve good electrical contacts while maintaining the bandgap large enough as to lower the potential barrier toward the transition to InP where the recombination is intended to occur.…”

“…In order to avoid these drawbacks, we developed a contact area that consists of an axial extension of the p-doped InP with p-doped InAs x P 1– x , where the As content is increased gradually in a continuous linear progression during 15 min of growth until AsH 3 and PH 3 fractions are the same (Figure a). Ohmic contacts can be established on p-doped InAsP and InAs. , In the top segment of the nanowires, we measured by energy dispersive X-ray spectroscopy (EDS), a fraction of As in the NW increasing from 0 up to 0.56 ± 0.06, which is in good accordance to the molar fractions used. We limited the As content in order to achieve good electrical contacts while maintaining the bandgap large enough as to lower the potential barrier toward the transition to InP where the recombination is intended to occur.…”

Ohmic Contacts to p-Type III-V Semiconductors for the Base of Heterojunction Bipolar Transistors

“…The test structures were filled circular contacts with gaps between the contacts and a large-area metal field. The gap spacings were nominally 4,8,14,20,30,50, and 75 µm. Prior to metal deposition, pre-metallization surface treatments were performed, as indicated in each of the following sections.…”

“…The contacts that provided the lowest specific contact resistances both as-deposited and annealed were Pd/Ru/Au. (14). Also as observed for contacts to p-type InAs and InGaSb, Pd reacts uniformly with the InAsP, but it is necessary to limit its thickness to avoid deep reaction.…”

Selective Deposition of Ohmic Contacts to p-InGaAs by Electroless Plating

“…10 We have also found Pd to produce low contact resistances on p-InAs 11 and p-InAsP. 12 On GaAs, Pd has been shown to penetrate the native oxide and form a more intimate metal/ semiconductor interface. 13 This same phenomenon may also occur on other III-V materials and be part of the reason for the low contact resistances we have seen.…”