Quantitative off‐axis electron holography of GaAs p‐n junctions prepared by focused ion beam milling

Abstract

SummaryFocused Ion beam (FIB) prepared GaAs p-n junctions have been examined using off-axis electron holography. Initial analysis of the holograms reveals an experimentally determined builtin potential in the junctions that is significantly smaller than predicted from theory. In this paper we show that through combinations of in situ annealing and in situ biasing of the specimens, by varying the intensity of the incident electron beam, and by modifying the FIB operating parameters, we can develop an improved understanding of phenomena such as the electrically 'inactive' thickness and subsequently recover the predicted value of the built-in potential of the junctions.

Dopant profiling of focused ion beam milled semiconductors using off-axis electron holography; reducing artifacts, extending detection limits and reducing the effects of gallium implantation

“…Several articles have discussed electron holography experiments performed on GaAs samples containing p-n junctions [14,[27][28][29][30], for example, it is known that the inactive layer in these p-n junctions is dependent on the operating voltage of the FIB [31]. However, no experimental results have been published to show whether the inactive thickness in GaAs also depends on the dopant concentration.…”

Extending the detection limit of dopants for focused ion beam prepared semiconductor specimens examined by off-axis electron holography

“…For all of the specimens the electrically inactive thickness is found to be reduced by a factor of 2 when the FIB operating voltage is reduced from 30 to 8 kV which is consistent with previous observations of GaAs p-n junctions. 19 After the low temperature annealing the electrically inactive thickness has been almost completely removed for the specimens with dopant concentrations of 2 ϫ 10 18 and 1 ϫ 10 19 cm −3 . However, for the specimen with the dopant concentration of 2 ϫ 10 17 cm −3 , a large inactive thickness remains, even after multiple attempts to remove it using specimens prepared at different times, using different FIB operating voltages and different annealing temperatures up to 500°C.…”

A Small Spot, Inert Gas, Ion Milling Process as a Complementary Technique to Focused Ion Beam Specimen Preparation

“…Such "dead layer" formation is a major problem for studies of semiconductor properties in p-n junctions or magnetic materials (Cooper et al, 2009). Post-FIB, low energy, Ar ion milling is able to remove the Ga-contaminated layer because Ar is lighter than Ga and rarely forms chemical bonds with other elements (Unocic et al, 2010).…”