Temperature dependence of contact resistance of Au-Ti-Pd2Si-n+-Si ohmic contacts

We investigated temperature dependence of contact resistance of an Au-Ti-Pd2Si ohmic contact to heavily doped n+-Si. The contact resistance increases with temperature owing to conduction through the metal shunts. In this case, the limiting process is diffusion input of electrons to the metal shunts. The proposed mechanism of contact resistance formation seems to realize also in the case of wide-gap semiconductors with high concentration of surface states and dislocation density in the contact

Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine 8 PACS 85

Abstract. We consider the features of formation of AuTiPd ohmic contacts to p + -Si. Metallization was made by vacuum thermal sputtering of Pd, Ti and Au films onto the Si substrate heated up to 330 С. It is shown that the contact resistivity increases with temperature; this is typical of metallic conductivity. We suggest that the ohmic contact is formed owing to appearance of shunts at Pd deposition on dislocations or other structural defects. The number of shunts per unit area is close to the measured density of structural defects at the metalSi interface

The measurements of pulsed I–V-curves for silicon IMPATT diodes in the avalanche breakdown region

Some aspects of measurement of I–V-curves for IMPATT diodes are considered. There were determined the main parameters of the pulsed I–V-curves for IMPATT diodes: density of critical current, voltage step in the region of negative differential resistance and avalanche breakdown region. A method for determination of p–n junction-package thermal resistance that is required for calculation of IMPATT diode operating mode is given. A possibility to use DU magnitude for prediction of early failures of IMPATT diodes was demonstrated

Nanostructured antidiffusion layers in contacts to wide-gap semiconductors

The interrelation between the antidiffusion properties of titanium diboride films and their nanocrystalline structure is investigated. We made a valid assumption that the main reason for degradation of contacts with TiB2-based diffusion layers is diffusion through the TiB2 film through dislocations (formed due to stresses that appear in the course of ohmic contact formation) rather than chemical interaction. In that case, increase of mechanical strength of the TiB2 film at reduction of grain size will affect its diffusion strength more strongly than growth of diffusion penetrability owing to increase of grain boundary role. Our investigations showed that, to ensure maximal mechanical strength and heat stability, the size of nanocrystallites in films forming diffusion barriers has to lie within 3—15 nm. The TiB2 films with optimal nanocrystallite parameters can be obtained using magnetron sputtering with discharge current of 0,4 A and oxygen content in a target up to 8 at.%. Application of TiB2-based nanocrystal films as antidiffusion layers in contacts to wide-gap semiconductors makes it possible to raise heat stability of devices based on such semiconductors

Specificities of temperature dependence of saturation current of forward-biased Shottkey diodes TiBx–n–6HSiC

It is researched temperature dependences of forward branch of Shottkey diodes TiBx–n–6HSiC. It is detected that forward branch of voltage-current characteristic is described by exponential dependence for voltage interval of 0.05–0.4 V and temperature interval of 100–500 K. At that saturation current and characteristic energy are weakly dependent on temperature. It is shown that redundant component of silicon carbide Shottkey diodes has tunnel behavior, in spite of spatial charge region width into researched diodes is essentially greater than characteristic tunnel length

Temperature-dependent efficiency droop in InGaN-based light-emitting diodes induced by current crowding Temperature-dependent efficiency droop in InGaN-based light-emitting diodes induced by current crowding

Abstract Temperature-dependent internal quantum efficiency (IQE) of multiple quantum well InGaN/GaN light-emitting diodes (LEDs) has been investigated. IQE versus current relation is analysed using the modified rate equation model that takes into account the current crowding effect at different temperatures. The results of calculations are consistent with the fact that droop in IQE at higher currents originates from Auger recombination increased by current crowding. It is shown that unusual experimentally observed temperature dependence of the efficiency droop can be explained by stronger lateral nonuniformity of carrier injection at low temperatures without any assumptions about carrier delocalization from In-rich regions in quantum wells