The University of Texas System

Terry J Mattord

Ben G Streetman

Dean P Neikirk

Michael H Gilbert, Sr

Ben G Treetman

Vijay P Kesan

Craig W Farley

A molecular beam epitaxy effusion cell for growing epitaxial layers upon a semiconductor substrate by control of a collimated beam of molecules generated from a source material in a high vacuum environment in order to control the hyper abrupt stoichiometry of the effusion flux. A heated control assembly is used to control the size of the exit openings of the effusion cell. The control assembly comprises a boroelectric heating member such as a grating having a plurality of holes and a perforated cover which are adjustable relative to one another. The grating includes an internal heating element.

Molecular beam epitaxy effusion cell

A heated view port for in-situ optical observation of a deposition chamber in a vessel under high vacuum application comprising a plurality of superimposed layers arranged in the shape of an annular band mounted around the view port substantially at the outer periphery thereof. The band includes a first layer of pyrolytic boron nitride, a second layer of pyrolytic graphite covering at least one surface of the pyrolytic boron nitride layer, an outer layer of pyrolytic boron nitride and two electrical contact terminals in contact with the pyrolytic graphite layer in an arrangement forming parallel resistive paths between the contact terminals. The terminal contacts are connected to an external source of electrical power.

Heater for high vacuum optical view port

A sublimating and cracking device which may be used to produce a collimated beam of molecules from a solid source. The device includes an elongated sublimating tube and an elongated cracking tube adapted to be axially oriented off axis to each other. The sublimating and cracking tubes are interconnected and heated in use.

Sublimating and cracking apparatus

A furnace having a sublimating section, a cracking section oriented off axis to the sublimating section, and a valve for controlling flux between the sections. The valve includes an annular plug having at least one longitudinal slot. The plug is retractable from a fully closed position where the slot is completely covered, to a fully open position where the slot is completely exposed. The slot becomes increasingly exposed as the plug is moved from the fully closed position to the fully opened position, thereby increasing flux from the sublimating section to the cracking section.

A device and method for producing an ultra pure molecular beam of elemental molecules utilizing a reduced thermal gradient filament construction in an effusion cell is provided. The effusion cell comprises a crucible having an open and a closed end and at least one heating filament distributed immediate the crucible. The at least one heating filament or filaments are provided having a first portion having a first pitch in proximal relationship to the open end of the crucible and having a second portion having a second pitch wherein the first pitch is of a higher spatial frequency than the second pitch. The heating filament is non-inductively wound about the crucible and positioned in conformity to the outside structure of the crucible. The heat shield is positioned proximate and about the crucible and heating filament or filaments. The heating filaments are connected to a controllable electric power supply producing a near constant temperature along the long axis of the crucible. By placing source material in the crucible and placing the crucible heating filaments and heat shield in a reduced pressure atmosphere and powering the heating filaments, a substantially constant temperature is produced along the crucible long axis resulting in an ultra pure molecular beam of elemental molecules of the source material.

Growing community of inventors

Red Rock, TX, United States of America

Terry J Mattord