Browsing by Author "Hopper, Richard"
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Item Open Access Accurate temperature measurements on semiconductor devices.(De Montfort University, 2010) Hopper, RichardSelf-heating can have a detrimental effect on the performance and reliability of high power microwave devices. In this work, the thermal performance of the gallium arsenide (GaAs) Gunn diode was studied. Infrared (IR) thermal microscopy was used to measure the peak operating temperature of the graded-gap structured device. Temperature measurements were experimentally validated using micro-thermocouple probing and compared to values obtained from a standard 1D thermal resistance model. Thermal analysis of the conventionally structured Gunn diode was also undertaken using high resolution micro-Raman temperature profiling, IR thermal microscopy and electro/thermal finite element modeling. The accuracy of conventional IR temperature measurements, made on semiconductor devices, was investigated in detail. Significant temperature errors were shown to occur in IR temperature measurements made on IR transparent semiconductors layers and low emissivity/highly reflective metals. A new technique, employing spherical carbon microparticles, was developed to improve the measurement accuracy on such surfaces. The new ‘IR microparticle’ technique can be used with existing IR microscopes and potentially removes the need to coat a device with a high emissivity layer, which causes damage and heat spreading.Item Metadata only The effect of transparency within a semiconductor on emissivity mapping for thermal profile measurements of a semiconductor(IET, 2007-03-08) Oxley, C. H.; Hopper, RichardThe paper reports on infra-red (IR) measurements made on silicon and gallium arsenide substrates which are transparent to IR radiation. The work showed that the measured emissivity is dependent on the wafer back-face technology, for example, a gold heat-sink or epoxy attachment. The work also indicated that the measured emissivity for the thermal mapping of a device is a function of the emitted radiation from the front, back face and layer interfaces, as well as internally reflected radiation and will be dependent on the thickness of the semiconductor wafer. Experimental work has shown that the two-temperature emissivity correction method will give a very accurate value of the total surface emissivity received from the sample.Item Metadata only Improved infrared (IR) microscope measurements and theory for the micro-electronics industry.(Elsevier, 2010) Oxley, C. H.; Hopper, Richard; Hill, G.Item Metadata only Improved Infrared (IR) Microscope Measurements for the Micro-electronics Industry(2008-09) Oxley, C. H.; Hopper, Richard; Evans, G. A.Infrared (IR) measurements of the surface temperature of electronic devices have improved over the last decade. However, to obtain more accurate surface temperatures the devices are often coated with a high emissivity coating leading to temperature averaging across the device surface and damage to the device. This paper will look at the problems of making accurate surface temperature measurements particularly on areas of semiconductor and will address the surface emissivity correction problem using novel measurement approaches.Item Metadata only Improved infrared thermal imaging of a CMOS MEMS device.(IEEE, 2010) Hopper, Richard; Haneef, Ibraheem; Ali, Syed Zeeshan; Udrea, Florin; Oxley, C. H.Item Open Access Infra-Red Thermal Measurement on a Low Power Infra-Red Emitter in CMOS Technology(IET, 2019-01-17) Pandey, P.; Oxley, C.; Hopper, Richard; Ali, Z.; Duffy, A. P.This paper presents high temperature characterisation of a novel infra-red (IR) emitter chip based on CMOS technology, using IR thermal microscopy. The performance and reliability of the thermal source is highly dependent on the operating temperature and temperature uniformity across the micro-heater which is embedded within the silicon dioxide membrane. To date, the accuracy of the IR measurement has been limited by the optical transparency of the semiconductor material forming the membrane, which has poor emissivity compared to a black-body source. In this paper, a high emissivity micro-particle sensor is used improve the accuracy of the temperature measurements. IR measurements on the emitter chip were validated with reference to temperature measurements made using an electrical technique where good temperature uniformity across the membrane heater was found.Item Metadata only Infrared radiance and temperature measurements on the mesa side of Gunn diodes(IEEE, 2008) Hopper, Richard; Oxley, C. H.; Seddon, R.; Foulger, R.; Priestley, N.Item Metadata only Measurement of the reflection and transmission properties of conducting fabrics at milli-metric wave frequencies.(IET, 2007-05-01) Williams, J. T.; Alabaster, C.; Hopper, Richard; Oxley, C. H.; Flora, H.; Eibeck, D.Item Metadata only Micro-Raman/Infrared temperature monitoring of Gunn Diodes.(IEEE, 2008) Hopper, Richard; Oxley, C. H.; Pomeroy, J. W.; Kuball, M.Item Metadata only Micro-Scale Infrared Thermal Characterisation of Electronic Devices(2010-04) Oxley, C. H.; Hopper, RichardItem Metadata only A novel method for more accurately mapping the surface temperature of ultrasonic transducers.(Elsevier, 2011) Axell, R.; Hopper, Richard; Jarritt, P. H.; Oxley, C. H.Item Metadata only Probe propels IR thermal microscopy to a new level(2011) Oxley, C. H.; Hopper, Richard; Prime, Dominic; Leaper, Mark C.; Evans, Gwynne; Levick, AndrewItem Metadata only Reduction of impact ionization in GaAs-Based Planar Gunn Diodes by Anode Contact Design(IEEE, 2012) Montes, Miguel; Dunn, G.; Stephen, A.; Khalid, A.; Li, C.; Cumming, D.; Oxley, C. H.; Hopper, Richard; Kuball, M.Item Metadata only Thermal measurement a requirement for monolithic microwave integrated circuit design(2008) Hopper, Richard; Oxley, C. H.The thermal management of structures such as Monolithic Microwave Integrated Circuits (MMICs) is important, given increased circuit packing densities and RF output powers. The paper will describe the IR measurement technology necessary to obtain accurate temperature profiles on the surface of semiconductor devices. The measurement procedure will be explained, including the device mounting arrangement and emissivity correction technique. The paper will show how the measurement technique has been applied to study the thermal performance of gallium arsenide (GaAs) MMIC configurations and also to GaAs Gunn diodes.Item Metadata only Thermal measurement of RF and microwave devices using a novel thermal probe.(IEEE, 2011) Hopper, Richard; Glover, James; Evans, Gwynne A.; Oxley, C. H.Item Metadata only Use of carbon micro-particles for improved infrared temperature measurement of CMOS MEMS devices.(IOP Publishing, 2010-04) Hopper, Richard; Haneef, Ibraheem; Ali, Syed Zeeshan; Udrea, Florin; Oxley, C. H.