Ge/Pd (Zn) Ohmic contact scheme on p-InP based on the solid phase regrowth principle

Abstract

A contact metallization scheme of Ge/Pd(Zn), based on the solid-phase regrowth principle, has been developed for the formation of Ohmic contact on p-InP. Typical contact resistivities of low 10−4 to low 10−5 Ω cm2 can be obtained after annealing at temperatures higher than 400 °C. Cross-sectional transmission electron microscopy study confirmed the solid-phase regrowth process in the InP substrate. Precipitates of trapped materials during solid phase regrowth have also been observed. A solid phase regrowth model is proposed to rationalize the electrical and metallurgical properties. This solid phase regrowth process is expected to form low resistance Ohmic contact on other In-based compound semiconductors.

Related Electrical and Metallurgical Properties of Pd/Zn/Pd/Ge and Pd/Zn/Pd/Au Contact Systems to p-InGaP

“…The obtained minimum resistivity values conform to the moderate doping level of the InGaP epitaxial layers ( p % 2 Â 10 18 cm --3 ) and in spite of the larger bandgap ($1.9 eV) of InGaP, they are fully comparable to those for alloyed Au(Be, Zn) [5,18] and non-alloyed Ge/Pd(Zn) [14,15] Ohmic contacts to p-type InP with similar doping concentration.…”

“…Most of the effort, however, has been devoted to the development of low-resistance, shallow, non-Au-based Ohmic contacts, particularly those where the Au contact layer is replaced by Pd. As far as we know, a comprehensive study of the solid-phase regrowth process [7] to form low-resistance non-spiking Pd-based contacts has been reported for GaAs and GaAlAs [8][9][10], InGaAs [11,12], InP and InGaAsP [13][14][15][16], but not for p-type InGaP.…”

Pd/Sb(Zn) and Pd/Ge(Zn) ohmic contacts on p-type indium gallium arsenide: The employment of the solid phase regrowth principle to achieve optimum electrical and metallurgical properties

“…12 Later, Pd/ Ge(Zn) contacts on p-InP with Zn evaporated were shown to exhibit resistivities comparable to the lowest values for Au-based metallizations on this material (ρ c ≥ 1 × 10 -5 Ωcm 2 ). 13 Record low resistivities (≈ 5 × 10 -6 Ωcm 2 ) were achieved on p-InP with Pd/Sb(Zn) contacts, which were shown to conform to the SPR principle. 14 In a preliminary paper, the authors reported both low contact resistivity (ρ c = 3-8 × 10 -7 Ωcm 2 ) and penetration depth (<50 nm) for Pd/Sb(Zn) and Pd/Ge(Zn) contacts with Zn evaporated on moderately doped In 0.53 Ga 0.47 As (p = 4 × 10 18 cm -3 ).…”

Formation Mechanism of Low Contact Resistance PdZn-based Ohmic Contacts for p-type InP

“…23,24) For the p-InP ohmic contacts, Wang et al developed PdGe(Zn) contacts using SPR process. 4) From the XRD and XTEM study of Sb/Zn/Pd contacts, Pd in the contact materials was found to react with InP to produce ternary Pd 2 InP compounds at the contact metals/InP interface. This compound was kinematically stable at 400…”

“…Wang et al 4) developed Pd/Zn/Pd/Ge ohmic contacts using the solid-phase regrowth technique and achieved the contact resistance as low as 4 × 10 −5 cm 2 by annealing at 500…”