Phase formation sequence in the Ti/InP system during thin film solid-state reactions

Abstract

International audienceThe metallurgical properties of the Ti/InP system meet a great interest for its use as a contact in the scope of various applications such as the Si Photonics. The investigations conducted on this system highlight the initiation of a reaction between the Ti and the InP substrate during the deposition process conducted at 100 °C. The simultaneous formation of two binary phases, namely, Ti$_2$In$_5$ and TiP, is attributed to the compositional gradient induced in the InP by the wet surface preparation and enhanced by the subsequent $in situ$ Ar$^+$ preclean. Once formed, the TiP layer acts as a diffusion barrier inhibiting further reaction up to 450 °C in spite of the presence of an important Ti reservoir. At higher temperature, however, i.e., from 550 °C, the reaction is enabled either by the enhancement of the species diffusion through the TiP layer or by its agglomeration. This reaction gives rise to the total consumption of the Ti$_2$In$_5$ and Ti while the TiP and In phases are promoted

Development of a CMOS-compatible contact technology for III–V materials and Si photonics

“…The solid-state reactions of several systems based either on InP or InGaAs have been extensively studied. [20][21][22][23][24][25][26] The Ti/InGaAs system has been investigated. 21,22) At low temperature-for temperatures below 250 °C-the Ti phase is the only crystalline phase in presence.…”

“…The Ti/InP system and its solid-state reactions were also studied. 23) It was observed that the reaction between the Ti film and the InP layer is initiated during the deposition process conducted at 100 °C. This reaction leads to the concomitant formation of two binary phases, namely Ti 2 In 5 and TiP.…”