Sains Malaysiana 48(6)(2019): 1201–1207

http://dx.doi.org/10.17576/jsm-2019-4806-07

Characterization of Graphene based Capacitive Microphone

(Pencirian Grafen berasaskan Mikrofon Sentuh Berkapasitor)

HASLINAWATI MOHD MUSTAPHA¹, M.F. MOHD RAZIP WEE¹, AHMAD RIFQI MD ZAIN^1,2 & MOHD AMBRI MOHAMED¹*

¹Institute of Microengineering and Nanoelectronic, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

²Harvard John A Paulson, School of Engineering and Applied Science, Harvard University, Cambridge, MA, United States of America

Received: 25 August 2018/Accepted: 15 January 2019

ABSTRACT

This research focuses on the design, fabrication and characterization of the graphene based capacitive microphone. Finite element analysis (FEA) is first simulated in order to design and study the proposed graphene based capacitive microphone. While the fabrication introduced MEMS technique in order to reduce the physical size, volume and cost without neglecting the performance. This study discusses on physical characteristics of graphene diaphragm for capacitive microphone. The fabrication of 200 nm air gap and the free-standing suspended graphene with the contribution of the van der Waals force between the graphene layer as a diaphragm and the substrate are presented in this study. The first stage involved in this study was the photolithography process of patterning electrodes with 4 different dimensions of diaphragm. The characterization was performed by using surface profilometer, optical microscopy, Raman spectroscopy and FESEM to evaluate the physical characteristics of the diaphragm. In the last stage, LCR meter was used to measure the capacitive change with different diameter of graphene diaphragm within frequency range of 20 Hz to 20 kHz. FEA analysis showed the good sensitivity against the frequency response for the largest proposed diameter of diaphragm.

Keywords: Capacitive microphone; frequency range; graphene diaphragm; MEMS

ABSTRAK

Kajian ini memberi tumpuan kepada reka bentuk, fabrikasi dan pencirian mikrofon kapasitif berasaskan grafen. Pada permulaan, FEA disimulasikan untuk mereka bentuk dan mengkaji mikrofon kapasitif berasaskan grafen. Manakala fabrikasi ini memperkenalkan teknik MEMS untuk mengurangkan ukuran fizikal, isi padu dan kos tanpa mengabaikan prestasi. Kajian ini membincangkan ciri fizikal diafragma grafen untuk mikrofon kapasitif. Kami membentangkan fabrikasi lubang udara sebanyak 200 nm dan grafen tergantung bebas dengan sumbangan kekuatan daya Van Der Waals antara lapisan grafen sebagai diafragma dan substrat. Tahap pertama akan melibatkan proses fotolitografi elektrod dengan 4 dimensi berlainan diameter diafragma. Penciriannya dilakukan oleh permukaan profilometer, mikroskop optik, spektroskopi Raman dan FESEM untuk menilai ciri-ciri diafragma. Di peringkat terakhir, meter LCR digunakan untuk mengukur perubahan kapasitif dengan diameter diafragma grafen yang berbeza dengan julat frekuensi 20 Hz hingga 20 kHz. Analisis FEA menunjukkan sensitiviti yang baik terhadap tindak balas frekuensi bagi diameter yang paling besar.

Kata kunci: Grafen diafragma; julat frekuensi; kapasitif mikrofon; MEMS

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*Corresponding author; email: ambri@ukm.edu.my