Compound semiconductor epitaxial substrate and method for producing the same

• US 20090166642A1
• Filed: 05/28/2007
• Published: 07/02/2009
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Nakano, Tsuyoshi
• Granted Patent: US 7,935,984 B2
• Time in Patent Office: Days
• US Class Current: 257/75
• CPC Class Codes: H01L 21/02395 Arsenides
• CPC Class Codes: H01L 21/02463 Arsenides
• CPC Class Codes: H01L 21/02546 Arsenides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 29/66462 with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT

Abstract

There are provided a higher-performance compound semiconductor epitaxial substrate having improved electron mobility characteristics and its production method. The compound semiconductor epitaxial substrate includes a channel layer in which electrons travel and an epitaxial layer on each of a front side and a back side of the channel layer, wherein a total p-type carrier concentration A (/cm²) per unit area in the epitaxial layer on the back side of the channel layer and a total p-type carrier concentration B (/cm²) per unit area in the epitaxial layer on the front side of the channel layer satisfy the following expression (1):

0<A/B≦3.5  (1)

wherein A=(a concentration of all p-type carriers in an active state due to an acceptor impurity contained in the epitaxial layer on the back side of the channel layer)×(a total thickness of the epitaxial layer on the back side), and B=(a concentration of all p-type carriers in an active state due to an acceptor impurity contained in the epitaxial layer on the front side of the channel layer)×(a total thickness of the epitaxial layer on the front side).

Claims

1. A compound semiconductor epitaxial substrate for a planar device, comprising:

a channel layer in which electrons travel; and

an epitaxial layer on each of a front side and a back side of the channel layer, wherein

a total p-type carrier concentration A (/cm²) per unit area in the epitaxial layer on the back side of the channel layer and

a total p-type carrier concentration B (cm²) per unit area in the epitaxial layer on the front side of the channel layer satisfy the following expression (1);

0<

A/B≦

3.5 

 

(1)

wherein A=(a concentration of all p-type carriers in an active state due to an acceptor impurity contained in the epitaxial layer on the back side of the channel layer)×

(a total thickness of the epitaxial layer on the back side), and

B=(a concentration of all p-type carriers in an active state due to an acceptor impurity contained in the epitaxial layer on the front side of the channel layer)×

(a total thickness of the epitaxial layer on the front side).

2. The substrate of claim 1, wherein the epitaxial layer on the front side of the channel layer includes a front-side active layer and a contact layer.

3. The substrate of claim 1, wherein the epitaxial layer on the back side of the channel layer includes a buffer layer.

4. The substrate of claim 1, wherein the epitaxial layer on the back side of the channel layer includes a buffer layer and a back-side active layer.

9. A method for producing the substrate of claim 1, comprising the step of:

growing an epitaxial layer on a template by a MOCVD method.

5. A compound semiconductor epitaxial substrate with a pseudomorphic-high electron mobility transistor structure having an InGaAs layer as a channel layer in which electrons travel, wherein an electron mobility of the InGaAs layer at room temperature (300 K) is not less than 9000 cm²/Vs.

6. The substrate of claim 5, further comprising:

a front-side active layer and a contact layer, each as an epitaxial layer on a front side of the channel layer.

7. The substrate of claim 5, further comprising:

a buffer layer as an epitaxial layer on a back side of the channel layer.

8. The substrate of claim 5, further comprising:

a buffer layer and a back-side active layer each as an epitaxial layer on a back side of the channel layer.