Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting
We present a systematic study on the influence of the miscut orientation on structural and electronic properties in the homoepitaxial growth on off-oriented β-Ga2O3 (100) substrates by metalorganic chemical vapour phase epitaxy. Layers grown on (100) substrates with 6° miscut toward the [001¯] direc...
| Main Authors: | , , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
AIP Publishing LLC
2019-02-01
|
| Series: | APL Materials |
| Online Access: | http://dx.doi.org/10.1063/1.5054943 |
| _version_ | 1818652201887727616 |
|---|---|
| author | R. Schewski K. Lion A. Fiedler C. Wouters A. Popp S. V. Levchenko T. Schulz M. Schmidbauer S. Bin Anooz R. Grüneberg Z. Galazka G. Wagner K. Irmscher M. Scheffler C. Draxl M. Albrecht |
| author_facet | R. Schewski K. Lion A. Fiedler C. Wouters A. Popp S. V. Levchenko T. Schulz M. Schmidbauer S. Bin Anooz R. Grüneberg Z. Galazka G. Wagner K. Irmscher M. Scheffler C. Draxl M. Albrecht |
| author_sort | R. Schewski |
| collection | DOAJ |
| description | We present a systematic study on the influence of the miscut orientation on structural and electronic properties in the homoepitaxial growth on off-oriented β-Ga2O3 (100) substrates by metalorganic chemical vapour phase epitaxy. Layers grown on (100) substrates with 6° miscut toward the [001¯] direction show high electron mobilities of about 90 cm2 V−1 s−1 at electron concentrations in the range of 1–2 × 1018 cm−3, while layers grown under identical conditions but with 6° miscut toward the [001] direction exhibit low electron mobilities of around 10 cm2 V−1 s−1. By using high-resolution scanning transmission electron microscopy and atomic force microscopy, we find significant differences in the surface morphologies of the substrates after annealing and of the layers in dependence on their miscut direction. While substrates with miscuts toward [001¯] exhibit monolayer steps terminated by (2¯01) facets, mainly bilayer steps are found for miscuts toward [001]. Epitaxial growth on both substrates occurs in step-flow mode. However, while layers on substrates with a miscut toward [001¯] are free of structural defects, those on substrates with a miscut toward [001] are completely twinned with respect to the substrate and show stacking mismatch boundaries. This twinning is promoted at step edges by transformation of the (001)-B facets into (2¯01) facets. Density functional theory calculations of stoichiometric low index surfaces show that the (2¯01) facet has the lowest surface energy following the (100) surface. We conclude that facet transformation at the step edges is driven by surface energy minimization for the two kinds of crystallographically inequivalent miscut orientations in the monoclinic lattice of β-Ga2O3. |
| first_indexed | 2024-12-17T02:18:15Z |
| format | Article |
| id | doaj.art-670ae35a8db24bac89422f6b452c5f51 |
| institution | Directory Open Access Journal |
| issn | 2166-532X |
| language | English |
| last_indexed | 2024-12-17T02:18:15Z |
| publishDate | 2019-02-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | APL Materials |
| spelling | doaj.art-670ae35a8db24bac89422f6b452c5f512022-12-21T22:07:19ZengAIP Publishing LLCAPL Materials2166-532X2019-02-0172022515022515-710.1063/1.5054943017992APMStep-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and facetingR. Schewski0K. Lion1A. Fiedler2C. Wouters3A. Popp4S. V. Levchenko5T. Schulz6M. Schmidbauer7S. Bin Anooz8R. Grüneberg9Z. Galazka10G. Wagner11K. Irmscher12M. Scheffler13C. Draxl14M. Albrecht15Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyHumboldt-Universität zu Berlin, Institut für Physik und IRIS, Zum Großen Windkanal 6, D-12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyFritz-Haber-Institut der Max-Planck-Gesellschaft, Theory Department, Faradayweg 4-6, 14195 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyFritz-Haber-Institut der Max-Planck-Gesellschaft, Theory Department, Faradayweg 4-6, 14195 Berlin, GermanyHumboldt-Universität zu Berlin, Institut für Physik und IRIS, Zum Großen Windkanal 6, D-12489 Berlin, GermanyLeibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, GermanyWe present a systematic study on the influence of the miscut orientation on structural and electronic properties in the homoepitaxial growth on off-oriented β-Ga2O3 (100) substrates by metalorganic chemical vapour phase epitaxy. Layers grown on (100) substrates with 6° miscut toward the [001¯] direction show high electron mobilities of about 90 cm2 V−1 s−1 at electron concentrations in the range of 1–2 × 1018 cm−3, while layers grown under identical conditions but with 6° miscut toward the [001] direction exhibit low electron mobilities of around 10 cm2 V−1 s−1. By using high-resolution scanning transmission electron microscopy and atomic force microscopy, we find significant differences in the surface morphologies of the substrates after annealing and of the layers in dependence on their miscut direction. While substrates with miscuts toward [001¯] exhibit monolayer steps terminated by (2¯01) facets, mainly bilayer steps are found for miscuts toward [001]. Epitaxial growth on both substrates occurs in step-flow mode. However, while layers on substrates with a miscut toward [001¯] are free of structural defects, those on substrates with a miscut toward [001] are completely twinned with respect to the substrate and show stacking mismatch boundaries. This twinning is promoted at step edges by transformation of the (001)-B facets into (2¯01) facets. Density functional theory calculations of stoichiometric low index surfaces show that the (2¯01) facet has the lowest surface energy following the (100) surface. We conclude that facet transformation at the step edges is driven by surface energy minimization for the two kinds of crystallographically inequivalent miscut orientations in the monoclinic lattice of β-Ga2O3.http://dx.doi.org/10.1063/1.5054943 |
| spellingShingle | R. Schewski K. Lion A. Fiedler C. Wouters A. Popp S. V. Levchenko T. Schulz M. Schmidbauer S. Bin Anooz R. Grüneberg Z. Galazka G. Wagner K. Irmscher M. Scheffler C. Draxl M. Albrecht Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting APL Materials |
| title | Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting |
| title_full | Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting |
| title_fullStr | Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting |
| title_full_unstemmed | Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting |
| title_short | Step-flow growth in homoepitaxy of β-Ga2O3 (100)—The influence of the miscut direction and faceting |
| title_sort | step flow growth in homoepitaxy of β ga2o3 100 the influence of the miscut direction and faceting |
| url | http://dx.doi.org/10.1063/1.5054943 |
| work_keys_str_mv | AT rschewski stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT klion stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT afiedler stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT cwouters stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT apopp stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT svlevchenko stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT tschulz stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT mschmidbauer stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT sbinanooz stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT rgruneberg stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT zgalazka stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT gwagner stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT kirmscher stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT mscheffler stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT cdraxl stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting AT malbrecht stepflowgrowthinhomoepitaxyofbga2o3100theinfluenceofthemiscutdirectionandfaceting |