In situ transmission electron microscopy of transistor operation and failure

Abstract

Microscopy is typically used as a post-mortem analytical tool in performance and reliability studies on nanoscale materials and devices. In this study, we demonstrate real time microscopy of the operation and failure of AlGaN/GaN high electron mobility transistors inside the transmission electron microscope. Loading until failure was performed on the electron transparent transistors to visualize the failure mechanisms caused by self-heating. At lower drain voltages, thermo-mechanical stresses induce irreversible microstructural deformation, mostly along the AlGaN/GaN interface, to initiate the damage process. At higher biasing, the self-heating deteriorates the gate and catastrophic failure takes place through metal/semiconductor inter-diffusion and/or buffer layer breakdown. This study indicates that the current trend of recreating the events, from damage nucleation to catastrophic failure, can be replaced by in situ microscopy for a quick and accurate account of the failure mechanisms.

Asymmetrical Contact Geometry to Reduce Forward-Bias Degradation in β-Ga2O3 Rectifiers

“…Some in situ Transmission Electron Microscopy images of devices operated to the failure point were taken using electron transparent functional specimens from the fabricated bulk β-Ga 2 O 3 Schottky diode using focused ion beam (FIB). [41][42][43] Electrical characterization was performed inside a field emission 200 kV FEI Talos F200X TEM equipped with energy dispersive spectroscopy (EDS) with 1.2 Å resolution. For thermal simulations, a 3-D finite element analysis was employed to calculate the temperature distribution.…”

In Situ Transmission Electron Microscopy Observations of Forward Bias Degradation of Vertical Geometry β-Ga2O3 Rectifiers

“…Electron transparent (∼100 nm thick) β-Ga 2 O 3 coupons were prepared and lifted out from the completed rectifiers using a Ga + Focused Ion Beam (FIB) in a Helios Nanolab DualBeam TM scanning electron microscope. [29][30][31] This process involved wire bonding of the micro-electromechanical system (MEMS) device on a TEM chip carrier and transfer of the sample onto this MEMS device. 29,30 At first, a coupon was lifted out from the bulk β-Ga 2 O 3 rectifiers and attached on a copper TEM grid, which was further thinned down to a 100 nm thick electron transparent state using the Ga + FIB.…”

“…[29][30][31] This process involved wire bonding of the micro-electromechanical system (MEMS) device on a TEM chip carrier and transfer of the sample onto this MEMS device. 29,30 At first, a coupon was lifted out from the bulk β-Ga 2 O 3 rectifiers and attached on a copper TEM grid, which was further thinned down to a 100 nm thick electron transparent state using the Ga + FIB. Thinning down of the coupon involves a series of ion beam accelerating voltages and a wide range of current steps from 21nA-72pA.…”

Review—Radiation Damage in Wide and Ultra-Wide Bandgap Semiconductors

“…Defects formed during manufacturing or by irradiation, as well as interfaces, may trap electrons and holes, resulting in charged defect states. At low ion fluences (<10 12 ions cm −2 , depending on ion energy and mass), damage regions from individual ions do not overlap, and the response to ions of specific mass and energy can be characterized in situ or ex situ using the known density of ion events and a variety of techniques, 44,[196][197][198][199][200][201][202][203][204][205][206][207][208][209][210][211] such as scanning transmission electron microscopy (STEM) to determine the nature and concentration of damage/defects. While amorphous tracks are not expected to form in the wide bandgap and ultra-wide bandgap semiconductors, local compositional variations, defects and strain fields are expected along the ion trajectories.…”