Electrodeposition of cuprous oxide on boron doped diamond electrodes

OPTICS AND OPTOELECTRONICS VOLUME: 16 |NUMBER: 2 |2018 |JUNE Elec odeposi ion o Cup ous Oxide on Bo on Doped Diamond Elec odes Mi osla BEHUL1, Ma ian VOJS1, Ma ian MARTON1, Pa ol MICHNIAK1, Ma io KURNIAWAN2, Ral PEIPMANN2, Cod u a Au elia VLAIC2, And eas BUND2, Robe REDHAMMER1 1Ins i u e o Elec onics and Pho onics, Facul y o Elec ical Enginee ing and In o ma ion Technology, Slo ak Uni e si y o Technology, Ilko ico a 3, 812 19 B a isla a, Slo ak Republic 2Ins i u ue We ks o echnik, FG Elek ochemie und Gal ano echnik, Fakul ae ue Elek o echnik und In o ma ions echnik, Technische Uni e si ae Ilmenau, Ki chho -S . 6, 98693 Ilmenau, Ge many mi osla .beh[email p o ec ed], ma ian. ojs@s uba.sk, [email p o ec ed], pa ol.mic[email p o ec ed], ma io.ku niaw[email p o ec ed], al .p[email p o ec ed], co[email p o ec ed], [email p o ec ed], ob[email p o ec ed] DOI: 10.15598/aeee. 16i2.2778 Abs ac . Nowadays, Cu2O is e y p omising elec- ode ma e ial o pho oelec ochemical applica ions. In his pape , we epo on he con ollable syn hesis o Cu2O single pa icles as well as compac laye s on Bo on Doped Diamond (BDD) elec odes using po en- ios a ic deposi ion in con inuous and pulse mode. The BDD laye s we e p epa ed wi h di e en B/C a ios in he gas phase in o de o in es iga e bo on doping le el in luence on he Cu2O p ope ies. The e ec o elec- odeposi ion condi ions such as deposi ion egime and pulse du a ion was in es iga ed as well. The Cu2O co - e ed BDD elec odes we e analysed by Scanning Elec- on Mic oscopy (SEM) and Raman spec oscopy. Im- p o emen in he homogenei y o he elec odeposi and emo al o clus e s we e achie ed when he pulse po- en ios a ic egime was used. Using he same pulse elec odeposi ion pa ame e s, we con i med he possibil- i y o con olling he deposi ion a e o Cu2O by a y- ing he BDD conduc i i y. Finally, we we e able o scale he size o Cu2O pa icles by changing he numbe o deposi ion pulses. The ob ained esul s ha e shown a g ea po en ial o con olling he mo phology, amoun , size and dis ibu ion o Cu2O ilms on BDD subs a es by changing he bo on doping le el and elec odeposi ion condi ions as well. The in es iga ions epo ed he ein allowed us o be e unde s and he deposi ion mecha- nism o Cu2O on BDD elec odes which could hen be used o p epa a ion o ac i e laye s o elec ochemical applica ions and in op oelec onic de ices such as sola cells and pho ode ec o s. Keywo ds Bo on doped diamond, cup ic oxide, chemical apo deposi ion, pulse pla ing. 1. In oduc ion Diamond possesses many excep ional p ope ies such as he highes ha dness and he mal conduc i i y, excellen wea esis ance, chemical ine ness and he lowes ic ion coe icien . The e o e, diamond ilms g own by Chemical Vapo Deposi ion (CVD) ound wide ange o applica ions in elec onics, op ics, elec ochemis y and o he ields [1], [2], [3] and [4]. In addi ion, con olled bo on doping enables o adjus conduc i i y which has a posi i e impac mainly on he sensi i i y and selec i i y o BDD elec odes used o elec ochemical applica- ions [5]. Elec ochemical eac ions pe o m mos ly a he in e ace be ween elec oly e solu ions and he elec odes su aces. The e o e, modi ica ion o he elec ode su ace mo phology is a key ac o o uning he elec ode pe o mance [6] and [7]. Elec odeposi ion o cup ous oxide (Cu2O) mic o- c ys als may be used o con ol su ace p ope ies o biosensing o bioca aly ic applica ions. Cu2O is well known as one o he s able oxide o ms o coppe which has a b ownish- ed colo and a bandgap o c 2018 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 239 OPTICS AND OPTOELECTRONICS VOLUME: 16 |NUMBER: 2 |2018 |JUNE 2.0–2.2 eV [8]. Cup ous oxide is an in e es ing subs i- u e o noble me al ca alys s owing o i s signi ican ca aly ic ac i i y [9]. O he ad an ages o Cu2O in- clude he abundance o he p ecu so ma e ials, non- oxic na u e and cos e ec i e syn hesis ou es. Cu2O exhibi s se e al a ac i e cha ac e is ics o op oelec- onic de ices such as sola cells, lase s and pho ode- ec o s due o i s high abso p ion coe icien and good majo i y ca ie mobili y [10] and [11]. BDD is e y p omising candida e as a subs a e o Cu2O based pho oelec odes due o chemical ine ness, mechanical s abili y, and i suppo s he cha ge sepa a ion wi hin he semiconduc o and acili a e he pho oca aly ic ac- i i ies in gene al [12] and [13]. Cu2O hin ilms can be p epa ed using a ious me hods including chemical deposi ion, eac i e e apo a ion, Chemical Vapo De- posi ion (CVD), he mal oxida ion and sol-gel [8]. In con as o o he syn hesis p ocesses elec osyn hesis is a ela i ely simple and e sa ile echnique ha is pe - o med a a mosphe ic p essu e and does no equi e high empe a u es. Mo eo e , i allows a good con- ol o he p oduc s by con olling pa ame e s such as po en ial, cu en densi ies, pH o p ecu so concen a- ion in he elec oly e. This wo k is aimed o demon- s a e he possibili y o elec odeposi ion o Cu2O pa - icles and ull laye s on he BDD elec odes. Fo he i s ime, he in luence o bo on doping le el on he Cu2O mo phology is in es iga ed. 2. Expe imen al Polyc ys alline BDD elec odes we e p epa ed by plasma enhanced Ho Filamen Chemical Vapo De- posi ion (HF CVD) [14]. Be o e he BDD deposi ion he silicon subs a es we e seeded in an ul asonic ba h in suspension o 50 mg nanodiamond powde (diame e < 10 nm, CAS No. 7782–40–3, Sigma Ald ich) in 1 l o demine alized wa e (18 MΩ) o 40 minu es. The BDD laye s wi h hickness o 300±50 nm we e deposi ed o 2 hou s in a CH4/H2gas mix u e wi h an addi ion o ime hylbo on a p ocess p essu e o 3 000 Pa. The B/C concen a ion in he gas phase was se up o 0, 2 000, 4 000, 8 000, 10 000, 15 000 and 20 000 ppm and he concen a ion o CH4in H2 o 1 %. The sub- s a e holde empe a u e 700 ◦C was moni o ed du - ing he g ow h p ocess by a he mocouple. Finally, BDD samples we e ixed in o p in ed ci cui boa d sup- po , elec ically connec ed by a sil e pas e and iso- la ed by a polyme pas e (ESL 240-SB) (Fig. 1). So- lu ion con aining 100 mM sodium ace a e, C2H3NaO2, and 100 mM coppe (II) ace a e, Cu(CH3COO)2, wi h pH o 5.6 was used o syn hesize he Cu2O. Elec ode- posi ion o Cu2O pa icles was conduc ed in a glass cell wi h a BDD wo king elec ode, pla inum coun e elec ode and a sil e /sil e chlo ide e e ence elec ode (Ag/AgCl 1 M sa u a ed KCl) using a BioLogic SP– 150 gal anos a /po en ios a . In he case o po en io- s a ic deposi ion, a po en ial o −1V was applied o 10 s and in he case o po en ios a ic pulse elec odepo- si ion, 5 pulses o −1V o 2 s wi h du y cycle o 50 % we e applied. The po en ios a ic and pulsed po en io- s a ic p o ocols we e chosen in o de o ha e simila o- al cha ge o bo h elec odeposi ion p ocedu es. P e- pa ed se ies o BDD laye s we e analyzed by scanning elec on mic oscopy and Raman spec oscopy a oom empe a u e. Scanning elec on mic og aphs o Cu2O laye s we e ob ained using a JEOL 7500F ins umen ope a ing a 10 kV. Mic o-Raman spec oscopy (Con- ocal Raman mic oscopy MonoVis a CRS 750/BX51 manu ac u ed by S&I Spec oscopy) spec oscopy was pe o med using an a gon lase (λ= 514.5 nm) as he exci a ion sou ce. Each p esen ed spec um is an a e - age o wen y con inuously acqui ed spec a wi h a col- lec ion ime o 3 seconds each. (a) (b) (c) (d) Fig. 1: P ocess o ixa ion o BDD elec odes in o he elec ode holde s – (a) elec ode holde , (b) connec ion o BDD elec ode using conduc i e sil e pas e, (c) applying o polyme isola ion pas e, (d) pho o o eal elec ode. 3. Resul s and Discussion Fi s , we ha e in es iga ed he di e ence be ween pulse and con inuous deposi ion. Fo his pu pose, he BDD elec ode wi h concen a ion B/C = 10 000 ppm and CH4/H2= 1 % was used (Fig. 3(a)). By applying he pulse deposi ion (Fig. 2), Cu2O g ains doubled in size compa ed o he no mal po en ios a ic deposi ion we e ob ained along wi h he emo al o clus e s and imp o ed homogenei y o he deposi (Fig. 3(c)). We suppose ha i is because each o he pulses ini ia es a new nuclea ion p ocesses on he su ace si e wi h he c 2018 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 240 OPTICS AND OPTOELECTRONICS VOLUME: 16 |NUMBER: 2 |2018 |JUNE 0 4 8 12 16 20 -10 -8 -6 -4 -2 0 2 4 J ( m A /c m 2 ) Time (seconds) Con inuous deposi ion Pulse deposi ion Fig. 2: E olu ion o he cu en densi y du ing he con inuous and pulse elec odeposi ion o Cu2O. Fig. 3: SEM mic og aphs showing (a) BDD subs a e be o e Cu2O deposi ion, (b) Cu2O laye deposi ed by con in- uous deposi ion (10 s) and (c) Cu2O laye deposi ed by pulse deposi ion (5×2 s). bes condi ions o elec odeposi ion which esul s in a mo e uni o m deposi ion. This is i s ep esen ed by he mo e conduc i e BDD laye and a e a homoge- neous co e ing also by he o med Cu2O g ains. This beha iou causes a mo e uni o m and as e deposi ion. On he o he hand, in he case o con inuous deposi ion sha pe Cu2O c ys als we e obse ed, which migh be mo e a ou able o elec ochemical eac ions in some cases (Fig. 3(b)). The p epa ed samples o con inuously and pulse de- posi ed Cu2O BDD laye s we e analyzed by Raman spec oscopy (Fig. 4). The bo on doping is ep esen ed in Raman spec a by wo b oad bands a app oxi- ma ely 500 cm−1and 1220 cm−1, which a e associa ed wi h inco po a ion o bo on in o he diamond la ice. The 500 cm−1maximum is a ibu ed o he local i- b a ional modes o he bo on pai s and he small shoul- de a 1320 cm−1is associa ed wi h polyc ys alline di- amond in highly bo on doped ilms [15] and [16]. Ra- 200 400 600 800 1000 1 200 1400 1600 B In e ns i y ( a. u .) G D B Si Cu 2 O Si Si Cu 2 O Cu 2 O Con inuous deposi ion Pulse deposi ion Raman shi (cm -1 ) Fig. 4: Raman spec a o Cu2O deposi ed on BDD elec odes wi h B/C = 10 000 ppm and CH4/H2= 1 % using po en ios a ic deposi ion and pulse po en ios a ic depo- si ion. 0 4 8 12 16 20 24 -12 -8 -4 0 4 + clus e s Cu 2 O laye Cu 2 O laye Cu 2 O pa icles B/C (ppm) 0 2 000 4 000 8 000 10 000 15 000 20 000 J ( m A /c m 2 ) Time (seconds) wi hou Cu 2 O Fig. 5: E olu ion o he cu en densi ies du ing he pulse elec- odeposi ion o Cu2O on BDD subs a es p epa ed by di e en B/C a ios. man peaks co esponding o Cu2O a e obse able a 152 cm−1, 216 cm−1and 630 cm−1[17]. The obse ed Raman signals indica e he p esence o Cu2O while no CuO peaks we e de ec ed. The de ec ed Raman peaks a e in good ag eemen wi h li e a u e alues o Raman modes o Cu2O nanos uc u es [8]. The b oad max- imum a 303 cm−1, sha p peak a 521 cm−1and he b oad one a 950 cm−1belong o he silicon subs a e [8]. In compa ison wi h a con inuous deposi ion, he pulse deposi ion exhibi s an inc ease o he Cu2O sig- nals and a dec ease o he o he peaks which is mos p obably caused by a hicke Cu2O laye . In he nex pa , we in es iga e he in luence o bo on doping le el on he elec odeposi ion o Cu2O. Figu e 5 shows e olu ion o he deposi ion cu en den- si ies du ing he pulse elec odeposi ion o Cu2O on he BDD samples wi h a ious bo on doping le els. In ou p e ious s udy, S o c e al epo ed a signi ican de- c ease o shee esis ance wi h inc ease o bo on con en c 2018 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 241 OPTICS AND OPTOELECTRONICS VOLUME: 16 |NUMBER: 2 |2018 |JUNE Fig. 6: SEM mic og aphs showing (a), (b) Cu2O c ys als, (c), (d) Cu2O laye , (e), ( ) Cu2O laye wi h clus e s. in diamond [18]. Thus he inc ease o bo on concen- a ion and ela ed highe elec ode conduc i i y and highe amoun o su ace ac i e si es accele a ed he elec odeposi ion o Cu2O on he BDD su ace. The enhanced BDD conduc i i y enables an inc ease o he o al elec ic cha ge passed h ough he subs ance and, ollowing he Fa aday’s law, a consequen inc ease o he mass deposi ed on he elec ode su ace. In he case o ully co e ed BDD subs a es wi h Cu2O laye , 8–11 % dec ease o cu en densi y was obse ed du - ing he pulse deposi ion. This phenomenon is caused by co e ing he mo e conduc i e BDD laye wi h he less conduc i e Cu2O laye . Figu e 6 shows he scanning elec on mic og aphs o Cu2O c ys als deposi ed on BDD elec odes wi h a i- ous bo on concen a ions a e pulse deposi ion shown in Fig. 5. On he elec ode wi h B/C = 0 ppm no deposi ed Cu2O was obse ed, which is p obably due o e y low BDD conduc i i y and insu icien cha ge ans e . On he su ace o elec odes wi h B/C = 2 000 ppm and 4 000 ppm, homogenously dis ibu ed Cu2O c ys als wi h diame e s in he ange o 1–3 µm we e obse ed. The elec odes wi h B/C = 8 000 and 10 000 ppm we e almos con inuously co e ed by Cu2O laye , and on he elec odes wi h a io B/C = 15 000 ppm and highe , he co e ing was e en dense and sphe ical clus e s on op o a compac Cu2O laye we e obse ed in addi ion. These esul s indica e a di- ec in luence o he elec ode conduc i i y de e mined by bo on doping le el on he o al cu en densi y and consequen mass anspo , hus in luencing densi y and mo phology o Cu2O on he BDD su ace p o iding an e ec i e ool o su ace p ope ies con olling. The Raman spec a (Fig. 7) show inc eased Cu2O peaks a 152 cm−1and a 216 cm−1in he case o elec odes wi h highe bo on doping le el [8]. This indica es he p esence o hicke laye s caused by as e g ow h on mo e conduc i e BDD subs a e. The inc ease in in ensi y o 500 cm−1and 1 220 cm−1 maxima ollows he inc ease in B/C a io in he gas mix u e du ing deposi ion o BDD ilms e idencing he inc easing doping le el. A peak a 1 332 cm−1 co esponding o he polyc ys alline diamond was also eco ded in spec a o he ilms wi h lowe and no bo on concen a ions [15]. 200 400 600 800 1000 1200 1400 1600 B In e n si y (a . u .) Si Cu 2 O Cu 2 OB/C (ppm) 20 000 15 000 10 000 8 000 4 000 2 000 0 Raman shi (c m -1 ) Si Si B D G Fig. 7: Raman spec a o Cu2O deposi ed on BDD elec odes wi h a ious B/C concen a ion and CH4/H2=1% using pulse deposi ion. Finally, we ied o con ol he size o he Cu2O laye g ains by a ying he du a ion and num- be o he pulses main aining he same cha ge. Fo his pu pose, we choose he elec ode wi h c 2018 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 242 OPTICS AND OPTOELECTRONICS VOLUME: 16 |NUMBER: 2 |2018 |JUNE B/C = 8 000 ppm whe e no Cu2O clus e s we e ob- se ed. Th ee di e en deposi ions consis ing o (1) i e pulses wi h a du a ion o 400 ms and du y cy- cle o 10 % (Fig. 8(a)), (2) en pulses wi h a du a ion o 200 ms and du y cycle o 5 % (Fig. 8(b)), and (3) wen y pulses wi h a du a ion o 100 ms du y cycle o 2.5 % (Fig. 8(c)) we e pe o med. SEM mic og aphs ha e shown ha he size o Cu2O g ains was success- ully scaled down by applying highe numbe o pulses wi h sho e du a ion. This phenomenon is caused by a e mina ion o pa icle g ow h and nuclea ion o new pa icles du ing nex pulse. Simila in luence o depo- si ion pulses on size o Cu2O pa icles was epo ed by Liau e al [19]. Based on he expe imen al esul s and heo e ical knowledge we can assume ha he numbe and size o g ains can be di ec ly a ec ed by he num- be and du a ion o he pulses, which oge he wi h he bo on doping le el gi e a g ea po en ial o con ol he amoun , size and dis ibu ion o Cu2O on BDD subs a e. Fig. 8: Mo phology o Cu2O laye s deposi ed using di e en pulses du a ions. The du a ion was se up o (a) 400 ms, (b) 200 ms and (c) 100 ms. 4. Conclusion In his s udy, we demons a ed he possibili y o con- ollable elec odeposi ion o Cu2O pa icles as well as compac laye s on he bo on doped diamond elec odes. The BDD elec odes ab ica ed wi h a ious B/C con- cen a ion in gas mix u e (0–20 000 ppm) we e used o he deposi ions o Cu2O by po en ios a ic pulse elec- odeposi ion. Compa ison o con inuous elec odepo- si ion wi h pulse elec odeposi ion showed signi ican enhancemen o he homogenei y using a pulse elec- odeposi ion. The in es iga ions o bo on doping le el in luence on he mo phology o Cu2O on BDD sub- s a e has shown se e al in e es ing esul s. In he case o non doped diamond, no Cu2O deposi ion was ob- se ed. In he case o B/C = 2 000–4 000 ppm, he Cu2O mic o pa icles we e obse ed and in he case o B/C > 8 000 ppm he BDD he su ace was ully co - e ed wi h a Cu2O laye . The ob ained esul s indica e a signi ican in luence o he B/C a io on he deposi- ion a e, densi y and he mo phology o Cu2O ilms caused by di e en BDD conduc i i y and su ace- ac i e si es dis ibu ion. Following he SEM in es i- ga ion, we also ound ha he elec odeposi ed lay- e s o Cu2O pa icles we e homogeneously dis ibu ed o e he whole BDD subs a e. Finally, we success- ully con olled he size o he Cu2O g ains by a ying he numbe and du a ion o he deposi ion pulses. The p esen ed in es iga ions ha e shown a g ea po en ial o con olling he mo phology, amoun , size and dis- ibu ion o Cu2O ilms on BDD subs a es h ough he change o bo on doping le el and elec odeposi ion condi ions as well. Acknowledgmen This wo k was inancially suppo ed by he Slo ak Re- sea ch and De elopmen Agency unde he con ac No. APVV-16-0124 and by he g an s o Slo ak Na- ional G an Agency No. 1/0887/16 and 1/0558/17. The au ho s a e also g a e ul o he suppo o he DAAD o unding he coope a ion and o he sup- po by he Thü inge G aduie en o de ung. This wo k was pa ially suppo ed by he p ojec „Roz oj yskumnej in as uk u y STU, p ojek c. 003STU- 2-3/2016“ by he Minis y o Educa ion, Science, Re- sea ch and Spo o he Slo ak Republic. The au ho s a e also g a e ul o he suppo o ITMS: 26240220084 (Uni e zi ny edecky pa k STU B a isla a). Ou hanks also belong o Ja osla Ko ac J . o suppo du ing Raman measu emen . Re e ences [1] WEI, Q. P., Z. M. YU, M. N. R. ASHFOLD, L. MA and Z. CHEN. 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Solid S a e Communica ions. 2000, ol. 115, iss. 12, pp. 669–673. ISSN 0038-1098. DOI: 10.1016/S0038-1098(00)00240-4. c 2018 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 244 OPTICS AND OPTOELECTRONICS VOLUME: 16 |NUMBER: 2 |2018 |JUNE [18] SVORC, L., D. JAMBREC, M. VOJS, S. BARWE, J. CLAUSMEYER, P. MICHNIAK, M. MARTON and W. SCHUHMANN. Doping Le el o Bo on-Doped Diamond Elec odes Con- ols he G a ing Densi y o Func ional G oups o DNA Assays. ACS Applied Ma e ials and In e aces. 2015, ol. 7, iss. 34, pp. 18949–18956. ISSN 1944-8244. DOI: 10.1021/acsami.5b06394. [19] LIAU, C. K. L. and P. C. TSENG. E - ec o cu en pulse on elec onic p ope ies o Cu2O ilms ab ica ed by elec ochemical deposi ion p ocess. Elec ochemica Ac a. 2015, ol. 182, iss. 1, pp. 781–788. ISSN 0013-4686. DOI: 10.1016/j.elec ac a.2015.09.166. Abou Au ho s Mi osla BEHUL was bo n in B a isla a, Slo akia. He ecei ed his M.Sc. om Mic oelec onics in 2014 and Ph.D. om Elec onics and pho onics in 2017. His esea ch in e es s include ca bon ma e ials, hin laye s deposi ion, elec ochemis y and elec onics. Ma ian VOJS was bo n in Spisska No a Ves, Slo akia. He ecei ed his M.Sc. om Elec onics in 2002 and his Ph.D. om Elec onics in 2009. His e- sea ch in e es s include deposi ion o diamond, ca bon s uc u es, DLC and cha ac e iza ion o mo phology, elec ical and elec ochemical p ope ies and Raman spec oscopy. Ma ian MARTON was bo n in B a isla a, Slo akia. He g adua ed in elec onics in 2004 and in 2008 he ecei ed his Ph.D. in elec on- ics and acuum echnology, bo h a STU in B a isla a. Cu en ly his esea ch deals wi h ca bon nanoma e ials, e.g. diamond, CNTs, CNWs and DLC. Pa ol MICHNIAK was bo n in T s ena, Slo- akia. He ecei ed his Ph.D. om Elec onics and Pho onics 2016. His esea ch in e es s include P epa- a ion o Ca bon Thin Films (Diamond, Ca bon Nanowalls) by Chemical Vapou Deposi ion. Ma io KURNIAWAN was bo n in Pema ang Sian a , Indonesia. He ecei ed his M.Sc. om Mechanical Enginee ing a he Uni e si y o Tokyo, Japan in 2013. His esea ch in e es s include nanoma- e ials, elec odeposi ion, op oelec onics, and ene gy con e sion. Ral PEIPMANN was bo n in Ka lsbu g, Ge many. He ecei ed his Ph.D. in Chemis y om Technical Uni e si y D esden in 2012. His esea ch in e es s include in insically conduc ing polyme s, co osion and co osion p o ec ion and simula ion. Cod u a Au elia VLAIC was bo n in Cluj- Napoca, Romania. She ecei ed he Ph.D. om Chemical Enginee ing in 2012. He esea ch in e es s include co osion p o ec ion, li hium ion ba e ies and elec odeposi ion om ionic liquids. And eas BUND was bo n in Pue lingen, Ge - many. He ecei ed his diploma om he Uni e si y o Saa land in 1995. His esea ch in e es s include undamen al and applied elec ochemis y. Robe REDHAMMER was bo n in B a isla a, Slo akia. He ecei ed his Ph.D. om elec onics and acuum echnology in 1993. His esea ch in e es s include nano echnology and nanoma e ials. c 2018 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 245