Mask-less lithography of diamond films using shaped ultrafast UV pulses

摘要

Summary form only given. Atomic-scale manipulation of carbon based surfaces, such as diamond, has an enormous potential for the construction of future nano-scale, photonic and optoelectronic devices. Diamond, when compared to other group IV covalent semiconductors, is particularly interesting; not only its tightly packed and strongly bound crystal lattice is an ideal environment for extreme physics, but it also offers advantages in terms of heat conductivity, hardness and transparency for multitude of applications. The development of diamond transistors [1], single photon sources for quantum computation based on diamond [2] or high power diamond optics and lasers [3] have benefited from developments on high precision diamond processing greatly.We have observed that surface excitation by ultrashort UV laser pulses provides a novel method for processing diamond surfaces with nanometre accuracy [4]. Among its properties, the fact that the process is graphite-free and produced by non-linear optical interaction [5], enables high-speed nano-machining without the need of complex chemical processes while the spatial resolution can potentially go beyond the diffraction limit. This process, laser induced desorption (LID), differs from laser ablation by lower incident fluence or intensity on the sample, and by removing material by bond breaking and ejection of surface species via excited quanta instead of thermomechanical or electrostatic forces. In the first demonstrations, picosecond and nanosecond laser pulses were used with energies as low as 1 nJ, suggesting that the ejection process does not seem to have a threshold to occur. However, the etching rate depends on the intensity of the impinging pulse because the process relies on two-photon absorption [4, 5]. This low pulse energy/high intensity requirement can be met by the use of high repetition rate ultrafast UV lasers in combination with programmable digital micro-mirror device (DMD) lithographic techniques, opening the doorway to arbitrary and complex manipulation of diamond surfaces at atomic scales in a simple and rapid manner.In this presentation, we will show progress on the fabrication of complex structures in diamond surfaces with high accuracy (sub-10 nm, as shown in Figure 1) utilizing mask-less lithographic techniques and femtosecond UV excitation. We believe that this novel process will allow for the rapid fabrication of complex 3D photonic devices based on diamond with nanometer resolution.