Nanoscopic voltage distribution of operating cascade laser devices in cryogenic temperature

• Published in: Journal of microscopy (Oxford) 2016-06, Vol.262 (3), p.226-231
• Main Authors: DHAR, R.S., BAN, D.
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; cryogenic temperature; Measurement techniques; nanoscopic probing; Product safety; quantum cascade lasers; scanning voltage microscopy; Temperature
• ISSN: 0022-2720; 1365-2818
• DOI: 10.1111/jmi.12356

Summary A nanoscopic exploratory measurement technique to measure voltage distribution across an operating semiconductor device in cryogenic temperature has been developed and established. The cross‐section surface of the terahertz (THz) quantum cascade laser (QCL) has been measured that resolves the voltage distribution at nanometer scales. The electric field dissemination across the active region of the device has been attained under the device's lasing conditions at cryogenic temperature of 77 K. Lay description Nanotechnology forms the basis of electronic goods in today's scientific world and to stay at par we thrive to push for the advancement of technology leading to nanodevices and their characterisation. But, this is only possible if we can carefully characterize and analyse the concerns and issues in nanodevices and eliminate them in future, for improved nanodevices. This brings the requirement and interest in instruments that can measure nanodevices. A nanoscopic measurement technique has been developed and established with a high precision scientific instrument‐based measurement technique on the atomic force microscopy (AFM) system. The cross‐section surface of a nanodevice known as terahertz (THz) quantum cascade laser (QCL) has been measured at nanometer scales for voltage distribution across the device. The device operation is divided into different section depending on the applied voltage bias onto the device. The laser‐based nanodevice is operating (lases) when measurement is carried out to observe the change in voltage across the device. As the device lases only at cryogenic condition, major concern with this particular device, the nanoscopic measurement is performed at cryogenic condition of 77 K when the device is lasing. The electric field due to the voltage distribution across the active region of the nanodevice is also acquired under lasing condition, which is observed to be non‐linear across for the current plateau region of operation of the device.