Characterization and Improvements to Porous Silicon Processing for Nanoenergetics

Abstract

Sensors and Electron Devices Directorate, ARLApproved for public release; distribution unlimited. ii REPORT DOCUMENTATION PAGEForm Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) February 20092. REPORT TYPE ARL-TR-4717 SPONSOR/MONITOR'S ACRONYM(S) 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. SUPPLEMENTARY NOTES ABSTRACTNano-porous silicon offers a large surface area to volume ratio typical of nano materials and contains a network of pores that can be filled with oxidant. When a silicon fuel source is combined with an oxidant on the nano-scale, kinetic limitations of silicon oxidation are overcome and an explosive reaction is realized. We present a characterization of lightly doped p-type silicon for nanoenergetic porous silicon (PS) applications. Using gas adsorption measurements and gravimetric techniques, we characterize pore size, porosity, specific surface area, and thickness of PS thin films. Additionally, we report on the energetic reaction of the PS/oxidant system and mechanical stability of PS formed under several etch conditions including varied etch current, drying techniques, and annealing. Prior research has not focused on sample preparation methods of PS for gas adsorption measurements, but results presented here indicate that the method of PS sample preparation for gas adsorption isotherm analysis impacts the results. We find that a newly reported gravimetric technique for PS parameter characterization is inconsistent with expected PS property trends for lightly doped p-type Si.

Microstructural characterisation of metallurgical grade porous silicon nanosponge particles

“…Mesoporous and nanoporous Si are currently being investigated for drug delivery applications [4][5]. Nanoporous Si has also recently been investigated for applications as an energetic material [6][7]. Energetic materials are an important component of military defence systems and since metallurgical grade PS is relatively inexpensive, successful characterisation and tailoring of the material could prove critical for new applications development in this field and many others.…”

Nanoporous Silicon Ignition of JA2 Propellant

“…Previous open-air initiations of the on-chip silicon/perchlorate reaction resulted in large plumes of bright material rapidly emanating from the chip (13,15). It was expected that such a hot plume of gases and particles would easily ignite JA2 propellant.…”

“…The nanoporous silicon chips for this study were prepared by an electrochemical etch (13)(14)(15). This method provided an etched region on the chip with a multitude of fine pores in the silicon.…”

A Decade of Porous Silicon as Nano‐Explosive Material

“…Nano-explosive devices are based on porous silicon prepared using an electrochemical etch technique, usually in a HF:Ethanol electrolyte. The pores of the porous region are impregnated with an oxidizer, and when heat or energy is applied to the device, a strong exothermic reaction occurs [12].…”