Calibrated scanning spreading resistance microscopy profiling of carriers in III–V structures

• Published in: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 2001-07, Vol.19 (4), p.1662-1670
• Main Authors: Lu, R. P., Kavanagh, K. L., Dixon-Warren, St. J., Kuhl, A., SpringThorpe, A. J., Griswold, E., Hillier, G., Calder, I., Arés, R., Streater, R.
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition; Electronic density of states; Heterojunction bipolar transistors; Molecular beam epitaxy; Optoelectronic devices; Schottky barrier diodes; Secondary ion mass spectrometry; Semiconducting indium phosphide; Semiconducting silicon compounds; Semiconductor junctions
• ISSN: 0734-211X; 1071-1023; 1520-8567
• DOI: 10.1116/1.1387458

Two-dimensional carrier profiling using scanning spreading resistance microscopy (SSRM) has recently been reported for Si- and InP-based structures. In this article, we report SSRM measurements solely on III–V material-based structures. We have studied GaAs and InP doping staircase structures, prepared using molecular-beam epitaxy. These structures were then used as calibration standards for the profiling of carrier density in state-of-the-art III–V-based optoelectronic devices. We discovered that SSRM data on GaAs can be obtained with either polarity; however, only one polarity (positive or negative sample bias for n- or p- GaAs , respectively) produces SSRM results that show quantitative correlation with dopant concentration as determined by secondary ion mass spectrometry (SIMS). In comparison, SSRM measurements using both bias polarities on n- InP correlates well with SIMS, while p- InP exhibits a similar polarity dependence to p-type GaAs. A physical model based on a Schottky junction is proposed to explain these results. We also report calibrated SSRM measurements on GaAs and InP heterojunction bipolar transistor structures.