Low-temperature (330 °C) crystallization and dopant activation of Ge thin films via AgSb-induced layer exchange: Operation of an n-channel polycrystalline Ge thin-film transistor

Abstract

Ge thin films have been prepared by layer-exchange metal-induced crystallization using AgSb alloy as a catalyst. Not only the crystallization of Ge, but also the incorporation of Sb atoms into the crystalline Ge layer and their activation have been realized during the process at a temperature as low as 330 °C. Thin-film transistors have been fabricated using the Ge thin films as channel layers and the operation of an n-channel transistor with an on/off ratio of over 300 has been demonstrated.

Strain effects on polycrystalline germanium thin films

“…The performances of metal–oxide–semiconductor field-effect transistors (MOSFETs) based on a single-crystal Ge-on-insulator structure, formed using a single-crystal wafer 3 – 5 and/or high-temperature process (> 900 °C) 6 , 7 , surpassed those of Si MOSFETs. Low-temperature syntheses of Ge thin-film transistors (TFTs) have been achieved using conventional solid-phase crystallization (SPC) 8 – 11 , laser annealing 12 , seed layer technique 13 , and metal-induced crystallization 14 – 16 . Although these methods are potentially useful to expand the application of Ge, the crystallinity of the resulting polycrystalline Ge (poly-Ge) is still insufficient to increase the performances of Ge TFTs over those of Si MOSFETs.…”

Improving carrier mobility of polycrystalline Ge by Sn doping

“…Many crystallization techniques have been developed, including solid-phase crystallization (SPC) 14 – 16 , laser annealing 17 , 18 , chemical vapor deposition 19 , 20 , flash-lamp annealing 21 , the seed layer technique 22 , and metal-induced crystallization 23 – 25 . By using these techniques, Ge-TFTs have been fabricated on thermally oxidized Si 21 , 26 , 27 , glass 28 – 31 , and even flexible substrates 22 , 32 . Since gate stack technology for Ge has developed sufficiently 8 , recent Ge-TFTs performance is limited by the properties of the poly-Ge thin film itself 21 , 22 , 26 – 32 .…”

Influence of grain boundaries on the properties of polycrystalline germanium

“…[18][19][20][21][22][23][24][25][26][27][28] Ge-TFTs have been established using poly-Ge formed by solid-phase crystallization (SPC), [29][30][31] laser annealing, 32 seed layer technique, 33 and metal-induced crystallization. [34][35][36][37] However, poly-Ge generally has a high hole concentration due to defect-induced acceptors and a low hole mobility due to grain boundary (GB) scattering, 18,38 limiting the TFT performance.…”