Atomic layer deposition of transparent semiconducting oxide CuCrO₂ thin films

Abstract

Atomic layer deposition (ALD) is a vital gas-phase technique for atomic-level thickness-controlled deposition of high-quality thin films on various substrate morphologies owing to its self-limiting gas-surface reaction mechanism. Here we report the ALD fabrication of thin films of the semiconducting CuCrO2 oxide that is a highly prospective candidate for transparent electronics applications. In our process, copper 2,2,6,6-tetramethyl-3,5-heptanedionate (Cu(thd)2) and chromium acetyl acetonate (Cr(acac)3) are used as the metal precursors and ozone as the oxygen source. Smooth and homogeneous thin films with an accurately controlled metal composition can be deposited in the temperature range of 240-270 o C; a post-deposition anneal at 700-950 o C i n a n A r atmosphere then results in well crystalline films with the delafossite structure. Electrical transport measurements confirm the p-type semiconducting behavior of the films. The direct bandgap is determined f r o m U V -v i s s p e c t r o p h o t o m e t r i c m e a s u r e m e n t s t o b e 3 . 0 9 e V . T h e observed transmittance is greater than 75% in the visible range.

Transparent conductive CuCrO2thin films deposited by pulsed injection metal organic chemical vapor deposition: up-scalable process technology for an improved transparency/conductivity trade-off

“…Several methods were reported in the literature for the synthesis of CuCrO 2 : solid-state reaction (SS), 17,[20][21][22][23][24][25][26][27][28][29][30] sol-gel (SG), [31][32][33][34][35][36][37] pulsed laser deposition (PLD), [38][39][40][41][42] magnetron sputtering (MS) 16,[43][44][45][46] and chemical vapor deposition (CVD) including spray pyrolysis. [47][48][49][50] A summary of the electrical and optical properties versus the synthesis methods and the process temperature is given in are obtained with the films deposited by sol-gel, due to the low carrier concentration. The required high processing temperatures exclude the direct involvement of SS and SG for the fabrication of transparent electronic devices on transparent substrates like glass or plastic.…”

Synthesis and characterization of AgFeO2 delafossite with non-stoichiometric silver concentration

“…Delafossites are a promising class of materials which have applications as transparent semiconducting oxides, catalysts, luminescent materials, p-type semiconductors used in solar cells, optoelectronic devices, transparent photodiodes, batteries [1][2][3][4][5][6][7], etc. Even though much work has been carried out on the cuprate family of delafossites, especially about CuFeO 2 [8], little is known about the structural, electronic and magnetic properties of its silver counterpart AgFeO 2 .…”

“…Among methods of producing silver delafossite materials, it may be distinguished as: (1) low-temperature methods (e.g., hydrothermal synthesis, metathetical reaction, oxidizing fl ux reaction, sol-gel) [10][11][12][13][14], (2) high-temperature synthesis (e.g., solid-state reaction [15][16][17][18][19]) and (3) thin fi lm techniques (e.g., atomic layer deposition, pulsed laser deposition (PLD), chemical vapour deposition (CVD), RF sputtering [6,[20][21][22]). However, they do not always allow obtaining compounds of high purity.…”

Transparent ferrimagnetic semiconducting CuCr2O4 thin films by atomic layer deposition

“…The pulse times were fixed at 2 s for all the three precursors (two metal precursors and ozone), followed by a 3 s long N 2 purge based on our work on delafossite CuCrO 2 films, 30 and all the depositions were carried out at 250…”

“…As a starting point for the work, we utilize the detailed ALD growth parameters we recently optimized for the deposition of delafossite CuCrO 2 thin films. 30 For the deposition of CuCr 2 O 4 thin films, copper 2,2,6,6-tetramethyl-3,5-heptanedionate (Cu(thd) 2 ) and chromium acetyl acetonate (Cr(acac) 3 ) were used as metal precursors and ozone as the oxygen source; the depositions were carried out in a commercial hot-wall flow-type F-120 ALD reactor (ASM Microchemistry Ltd., Finland). The reactor was operated under a nitrogen (99.9995%) pressure of 2-3 mbar produced with a NITROX UHPN 3000 nitrogen generator.…”