TECHNICAL FIELD

The present invention relates to a p-type oxide semiconductor. Also, the present invention relates to a method for manufacturing a p-type oxide semiconductor. The present invention also relates to a semiconductor device including a p-type oxide semiconductor. Furthermore, the present invention relates to a semiconductor system including a p-type oxide semiconductor.

BACKGROUND ART

As a switching device of the next generation achieving high withstand voltage, low losses, and high temperature resistance, semiconductor devices using gallium oxide (Ga2O3) with a large band gap attract attention and are expected to be applied to power semiconductor devices including an inverter. Also, gallium oxide is expected to be applied to a light emitting and receiving element such as a light emitting diode (LED) and a sensor, since gallium oxide has a wide band gap. According to NPL 1, such gallium oxide has a band gap that may be controlled by forming mixed crystal with indium or aluminum singly or in combination and such a mixed crystal is extremely attractive materials as InAlGaO-based semiconductors. Here, InAlGaO-based semiconductors refers to InXAlYGaZO3(0≤X≤2, 0≤Y≤2, 0≤Z≤2, X+Y+Z=1.5˜2.5) and can be viewed as the same material system containing gallium oxide.

In recent years, gallium oxide based p-type semiconductors have been studied. For example, PTL 1 describes a base showing p-type conductivity to be obtained by forming a β-Ga2O3-based crystal by floating zone method using MgO (p-type dopant source). Also, PTL 2 discloses to form a p-type semiconductor by using an ion implantation of a p-type dopant into α-(AlxGa1-X)2O3single crystalline film obtained by Molecular Beam Epitaxy (MBE) method. However, NPL 2 discloses that a p-type semiconductor was not obtained by the methods disclosed in PTLs 1 and 2 (NPL 2). In fact, there has been no reports of any success in forming p-type semiconductor by use of the methods disclosed in PTLs 1 and 2. Therefore, feasible p-type oxide semiconductor and a method of manufacturing a p-type oxide semiconductor have been desired.

Also, NPLs 3 and 4 disclose a use of Rh2O3or ZnRh2O4as a p-type semiconductor, for example. Nevertheless, Rh2O3has a problem that the raw material concentration becomes thin, which affects forming films. It was difficult to produce a single crystal of Rh2O3even if using an organic solvent. Also, when Hall effect measurement was conducted, Rh2O3and ZnRh2O4were not determined to be p-type or the measurement itself could not be done. Further, for example, Hall coefficient of these semiconductors were measurement limit (0.2 cm3/C) or less and they were not useful at all. As for ZnRh2O4has a low mobility and a narrow band gap and thus, cannot be used as LED or power devices. Therefore, Rh2O3and ZnRh2O4were not necessarily satisfactory.

CITATION LIST

Patent Literature

PTL 1: JP2005-340308A

PTL 2: JP2013-58647A

Non Patent Literature

NPL 1: Kaneko, Kentaro, “Fabrication and physical properties of corundum structured alloys based on gallium oxide”, Dissertation, Kyoto Univ., March 2013

NPL 2: Tatsuya, Takemoto, EE Times, Japan “power device gallium oxide” Thermal conductivity, p-type . . . overcoming issues and putting it into practical use. [online], Retrieved Jun. 21, 2016, from http://eetimes.jp/ee/articles/1402/27/news028_2.html

NPL 3: F. P. KOFFYBERG et al., “optical bandgaps and electron affinities of semiconducting Rh2O3(I) and Rh2O3(III)”, J. Phys. Chem. Solids Vol. 53, No. 10, pp. 1285-1288, 1992

NPL 4: Hideo Hosono, “Functional development of oxide semiconductor” Physics Research, Electronic version, Vol. 3, No. 1, 031211 (Merger issue of September 2013 and February 2014)

SUMMARY OF INVENTION

Technical Field

It is an object of a present inventive subject matter to provide a new and useful p-type oxide semiconductor with electrical conductivity. It is also an object of a present inventive subject matter to provide a method of manufacturing a p-type oxide semiconductor.

Solution to Problem

As a result of keen examination to achieve the object, the present inventors learned that a method of manufacturing a p-type oxide semiconductor including: generating atomized droplets by atomizing a raw material solution containing at least a d-block metal in the periodic table and a metal of Group 13 of the periodic table; carrying the atomized droplets onto a surface of a base by using a carrier gas; and causing a thermal reaction of the atomized droplets adjacent to the surface of the base under an atmosphere of oxygen to form the p-type oxide semiconductor on the base can form a p-type oxide semiconductor with enhanced electrical conductivity. Furthermore, the obtained p-type oxide semiconductor is useful for semiconductor device using Ga2O3that has a wide band gap. They then found that such a p-type oxide semiconductor and the method of manufacturing the p-type oxide semiconductor are capable of solving the conventional problem as mentioned above.

After learning the above findings, the present inventors have made further research to complete the present invention. That is, the present invention relates to the followings.[1] A method of manufacturing a p-type oxide semiconductor including: generating atomized droplets by atomizing a raw material solution including at least a d-block metal in the periodic table and a metal of Group 13 of the periodic table; carrying the atomized droplets onto a surface of a base by using a carrier gas; and causing a thermal reaction of the atomized droplets adjacent to the surface of the base under an atmosphere of oxygen to form the p-type oxide semiconductor on the base.[2] The method of [1] above, wherein the d-block metal includes a transition metal.[3] The method of [1] or [2] above, wherein the d-block metal includes a metal of Group 9 of the periodic table.[4] The method of [3] above, wherein the metal of Group 9 includes rhodium, iridium or cobalt.[5] The method of any of [1] to [4] above, wherein the metal of Group 13 includes at least one metal selected from among indium, aluminum, and gallium.[6] The method any of [1] to [5] above, wherein the thermal reaction is conducted at a temperature that is 750° C. or lower.[7] A p-type oxide semiconductor including: a metal oxide as a major component, the metal oxide including a d-block metal in the periodic table and a metal of Group 13 of the periodic table.[8] The p-type oxide semiconductor of [7] above, wherein the d-block metal includes a transition metal.[9] The p-type oxide semiconductor of [7] or [8] above, wherein the d-block metal includes a metal of Group 9 of the periodic table.[10] The p-type oxide semiconductor of [9] above, wherein the metal of Group 9 includes rhodium, iridium, or cobalt.[11] The p-type oxide semiconductor of any of [7] to [10] above, wherein the metal of Group 13 includes at least one metal selected from among indium, aluminum, and gallium.[12] A semiconductor device including: a semiconductor layer including the p-type oxide semiconductor of any of [7] to [11] above; and an electrode.[13] The semiconductor device of [12] above, further including: an n-type semiconductor layer including as a major component an oxide semiconductor that includes a metal of Group 13 of the periodic table.[14] The semiconductor device of [13] above, wherein the metal of Group 13 includes at least one metal selected from among indium, aluminum, and gallium.[15] A semiconductor system including: the semiconductor device of any of [12] to [14] above.

Advantageous Effects of Invention

The p-type oxide semiconductor of a present inventive subject matter is sufficient in electrical conductivity and in semiconductor properties as a p-type semiconductor. The method of manufacturing a p-type oxide semiconductor of the present invention is capable of producing the above-mentioned p-type oxide semiconductor industrially advantageously.

