Growth of doped semiconductor monolayers

A method of doping a compound semiconductor single crystal layer being grown in monolayers on a heated substrate in a growth chamber by alternate introduction of source gases, the growth chamber being evacuated continuously at a continuous rate of evacuation throughout the whole method, the method comprising the steps of:

• (a) introducing a first source gas containing one constituent element of the compound into the growth chamber of at least a sufficient quantity for growing one monolayer, the supply of the first source gas being thereafter stopped and the growth chamber still being kept under the continuous rate of evacuation to evacuate residual of the first source gas;
• (b) introducing a second source gas containing another constituent element of the compound into the growth chamber of at least a sufficient quantity for growing one monolayer, the supply of the second source gas being thereafter stopped and the growth chamber still being kept under the continuous rate of evacuation to evacuate residual of the second source gas;
• (c) doping an impurity gas into the growth chamber, the impurity gas being of a particular type and having impurities which enter into sites in the monolayer being grown;
• (d) initially carrying out steps (a), (b) and (c) to grow a monolayer on the substrate and then growing monolayers one over the other by cyclically repeating steps (a), (b) and (c) to grow a new monolayer on the monolayer just previously grown;
• and
• (e) selectively implementing an order in which steps (a), (b) and (c) take place during each cycle of step (d) based on the particular type of impurity gas being doped and selectively timing when step (c) takes place with respect to the timing of steps (a) and (b) based on obtaining a desired dopant type for the monolayer being grown and a desired level of impurity concentration in the monolayer being grown,
• wherein the order in which steps (a), (b) and (c) take place is in accordance with an ascending numerical order of periodic table group types associated with the first source gas, the second source gas and the impurity gas, wherein the compound is a group III-V compound and the impurity gas contains an element belonging to one of the group II, group IV serving as a donor and group VI of the periodic table,
• whereby the continuous evacuation causes evacuation of residual waste of the first source gas, the second source gas, and the impurity gas.

A method of forming a single crystalline thin fill of a III-V or a II-VI compound semiconductor comprising the steps of:

• (a) continuously evacuating the interior of a crystal growth vessel at a constant rate of evacuation;
• (b) heating a substrate disposed in the crystal growth vessel to a temperature of from about 300 to 800 degrees C;
• (c) introducing into the crystal growth vessel, under a first deposition pressure of from about 10.sup..sup.-1 to 10.sup.-7 Pascal and for a first time period of from about 0.5 to 200 seconds, sufficient quantity of gaseous molecules of a first compound to form at least a single molecular layer of the first compound on the substrate, the first compound selected from the group consisting of group III and group II compounds respectively, which first compound contains a first constituent element of the III-V or II-VI compound semiconductor;
• (d) further introducing into the crystal growth vessel, under a second deposition pressure of from about 10.sup.-1 to 10.sup.-7 Pascal and for a second time period of from about 0.5 to 200 seconds, sufficient quantity of gaseous molecules of a second compound to form at least a single molecular layer of the second compound on the substrate, the second compound selected from the group consisting of group V and group VI compounds respectively, which second compound contains a second constituent element of the II-V or II-VI compound semiconductor;
• a single monolayer or a dimolecular layer growing in one cycle of said introduced gaseous molecules of first and second compounds corresponding to a saturation thickness in one cycle,
• the single-crystalline film being at least n times as thick as a single molecular layer of the compound semiconductor, where n is an integer of 1, 2 or larger to cause growth of a monocrystalline thin film of the compound semiconductor having dimensions as precise as a single molecular layer, the step (a) being continuous for evacuating any waste of the gaseous molecules introduced to form the first and second compound;
• introducing first dopant gaseous molecules, the first dopant gaseous molecules being of a first dopant compound containing a first dopant element of the GaAs compound semiconductor;
• introducing second dopant gaseous molecules, the second dopant gaseous molecules being of a second dopant compound containing a second dopant element of the GaAs compound semiconductor;
• and
• cyclically repeating the steps (c) and (d) while heating the substrate and continuously evacuating the growth chamber so as to cause growth of a single-crystalline thin film of the compound semiconductor having a thickness determined by the number of the cyclical repetitions, the thickness being dimensionally as precise as a monolayer.