Molecular beam epitaxy under vector strong magnetic field and in-situ characterization apparatus thereof
The present invention discloses a molecular beam epitaxy under vector strong magnetic field and an in-situ characterization apparatus thereof. The apparatus mainly consists of an inverted T-shaped ultrahigh vacuum growth and characterization chamber with a compact structure and a strong magnet. The inverted T-shaped vacuum chamber portion, which disposed in the room-temperature chamber of the strong magnet, includes a compact epitaxial growth sample stage, a device capable of rotating angle between the growth and magnetic field directions, and an in-situ characterization apparatus. The portion disposed below the strong magnet includes a molecular beam source component such as evaporation source, plasma source etc., and a vacuum-pumping system. The present invention surmounts effectively the technical problems between the small volume of the strong magnetic field chamber and numerous components of the growth and test system, and realizes the molecular beam epitaxial growth and in-situ characterization under the strong magnetic field.
1. A molecular beam epitaxy under a vector magnetic field and an in-situ characterization apparatus thereof, comprising a magnet, an inverted T-shaped ultrahigh vacuum growth and characterization chamber, an epitaxial growth sample stage, a linkage control system, an in-situ characterization and control apparatus, a molecular beam furnace source and a vacuum-pumping system;
wherein the magnet is a liquid-helium-free spiral magnet with a room-temperature chamber;
the inverted T-shaped ultrahigh vacuum growth and characterization chamber, which is disposed in a room-temperature chamber of the magnet, adopts a dual-layer multi-channel cooling structure with a thickness of 5 mm; and the space of the inverted T-shaped ultrahigh vacuum growth and characterization chamber, which is disposed below the magnet, is larger than that of the portion disposed in the room-temperature chamber of the magnet;
the epitaxial growth sample stage and the linkage control system are disposed in the room-temperature chamber of the magnet; and the rotation of the epitaxial growth sample stage is controlled by the linkage control system for changing an angle between the growth and the magnetic field direction from 0° to 90°;
the in-situ characterization and control apparatus is arranged in the room-temperature chamber of the magnet and is provided with a slope cooling unit, a probe detection apparatus, an up-down moving and rotating mechanism and a multifunctional joystick; and the slope cooling unit is an independently-operable cooling apparatus matched with the epitaxial growth sample stage; the slope cooling unit is provided with a liquid nitrogen pool; and the probe detection apparatus can move up and down and rotate for the switching from epitaxial growth and testing;
the molecular beam furnace source is provided with a molecular beam growth source component disposed below the magnet and can place a plurality of evaporation sources and radio-frequency gas plasma sources;
the vacuum-pumping system is provided with a mechanical pump, a molecular pump, an ion pump and a titanium pump, and the vacuum-pumping system is disposed below the magnet and used for providing ultrahigh vacuum with a vacuum degree higher than 10 −8 Pa.
2. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein an inner diameter of the room-temperature chamber is smaller than 10 cm.
3. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the magnet provides a magnetic field up to 15T with the homogeneity of 0.1%.
4. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the epitaxial growth sample stage adopts a reverse double-strand energizing radiation heating mode.
5. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the probe detection apparatus is equipped with more than six probes.
6. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the in-situ characterization mainly depends on an in-situ Hall effect and a magnetic resistance test, adopts an amperemeter of pA-grade and even fA-grade sensitivity and a voltmeter of nV-grade sensitivity, and adopts a bridge circuit designing method to connect the wire.
7. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the evaporation source adopts ferromagnets metals.
8. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the radio-frequency gas plasma source is oxygen or nitrogen.
9. The molecular beam epitaxy under the vector magnetic field and the in-situ characterization apparatus thereof according to claim 1 , wherein the evaporation source is heated from room temperature to a high temperature of 1600K and is controlled by an accurate programming (Proportional Integral Differential (PID) temperature control unit.