JP3417014B2 - Heterojunction Hall element - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high sensitivity heterojunction Hall element. 2. Description of the Related Art There is a Hall element as one of the magnetoelectric conversion elements. The Hall element is a magnetic sensor and is used as a rotation sensor or the like. Recently, a Hall element comprising a heterojunction of GaInAs and InP has been developed in response to a demand for higher performance of the Hall element (Shinobu Okuyama)
Proceedings of the 53rd Autumn Meeting of the Japan Society of Applied Physics
o. 3 (published by the Japan Society of Applied Physics, 1992), lecture number 16
a-SZC-16, p. 1078). This GaInAs heterojunction Hall element is said to have excellent temperature characteristics and sensitivity characteristics. A heterojunction between GaInAs and InP is
Conventionally, it is formed on an InP crystal substrate from the viewpoint of lattice matching. The carrier concentration of the GaInAs layer serving as the magnetic sensing layer is adjusted to obtain a desired device input resistance. In order to obtain a relatively high input resistance, undoping may be sufficient, but usually, the carrier concentration is adjusted by doping. As the dopant, a group VI element such as sulfur (S) or a group IV element such as silicon (Si) is used. The distribution (profile) of the carrier concentration in the depth direction also changes the characteristics of the Hall element. For example, G
The presence of a region having a low carrier concentration at the hetero interface with InP in the aInAs layer causes an increase in input resistance. This is because a low carrier region has a high resistance. Usually, a flat carrier concentration profile is desired. SUMMARY OF THE INVENTION InP and GaInAs
In order to form a heterojunction with the above, it is necessary to switch the group V source gas. Group V layer elements constituting a semiconductor are P and As
Because it is different. In the conventional MOCVD method, phosphine (PH ₃ ) is generally used for growing InP, and arsine (AsH ₃ ) is used for growing GaInAs. Following the InP growth to grow the GaInAs switch from PH ₃ to AsH _3. P from the growth system
In order to sufficiently discharge H ₃ , a certain interval is provided from the stop of the supply of PH _{3 to} the start of the supply of AsH ₃ . Even during this time interval, the growth layer is usually maintained at a high growth temperature. Therefore, the surface of the InP growth layer is altered due to evaporation of P and the like. The altered surface layer has a higher resistance.
When a GaInAs layer is subsequently deposited, a region having a high resistance is generated near the hetero interface. As a result, the carrier concentration is not constant in the depth direction than the surface of the GaInAs layer, and a “recess” is generated on the profile. Conventional InP / Ga
FIG. 3 shows the carrier concentration profile of the InAs heterojunction.
Is shown by a broken line. A heterojunction of GaInAs and InP may exhibit high electron mobility (for example, Kenjiro Onuma et al., Proceedings of the 53rd Autumn Meeting of the Japan Society of Applied Physics, No. 1 (published by the Japan Society of Applied Physics, 1992) , Lecture number 1
8a-ZE-3, page 283, or Hilde Har
dtdegen et al. Crystal Growth
h, Vol. 116 (1992), p. p. 521-5
23. ). However, high electron mobility has not been stably obtained. The generation of the high-resistance region is one of the factors that hinders stable manifestation of electron mobility. Further, the optimum heterocarrier concentration profile for obtaining high electron mobility has not been clarified yet. For this reason, the present situation is that the stable supply of the GaInAs / InP heterojunction Hall element with high product sensitivity is hindered. An object of the present invention is to provide Ga which is necessary for stable development of high electron mobility.
The purpose is to clarify the carrier concentration profile of the InAs / InP heterojunction material. According to the present invention, GaInAs is used.
A profile for increasing the carrier concentration from the layer surface to the heterojunction interface with InP is adopted. GaInA
The s / InP heterojunction is grown on a semiconductor single crystal substrate. An InP crystal can be used as a substrate due to lattice matching. The order of deposition on the substrate is not limited. However, InP
Should be deposited first as a buffer layer. This is for reducing the diffusion amount of impurities in the substrate into the magneto-sensitive layer. When the amount of impurities in the magneto-sensitive layer increases, the electron mobility decreases, which hinders an improvement in the sensitivity characteristics of the Hall element. The carrier concentration of the InP buffer layer is usually about 5 × 10 ^{16 to} 3 × 10 ¹⁷ cm ⁻³ . The carrier concentration in the InP buffer layer preferably decreases monotonously from the hetero interface to the substrate side. This is because an increase in the carrier concentration in the buffer layer causes insulation failure of the Hall element. A GaInAs magnetosensitive layer is grown on the InP buffer layer. A semiconductor layer for ohmic contact may be provided on the magneto-sensitive layer. The method of growing the InP layer and the Ga _x In _1-x As layer is not limited. Molecular beam epitaxial growth (MB
E) or MOCVD (organic metal pyrolysis vapor phase epitaxy) may be used. MO ・ MBE combining MBE and MOCVD
The law can be applied. Further, it is not necessary to provide each layer forming a heterojunction by a single growth method. [0010] The carrier concentration of the GaInAs free layer monotonically increases in the direction from the surface to the heterojunction interface with InP. A gradient is applied to the carrier concentration so that a “concave portion” corresponding to the conventional high-resistance region is not generated in the carrier concentration profile near the hetero interface. The carrier concentration near the hetero interface is higher than that on the surface of the GaInAs free layer. Preferably, the carrier concentration on the surface of the GaInAs free layer is 5 ×
The range is 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁶ cm ⁻³ or less.
The carrier concentration in the vicinity of the interface of the hete is 8 × 10 ¹⁶ cm ^−3.
It is preferably at least 2 × 10 ¹⁷ cm ⁻³ . The preferred carrier concentration is 5 × 10 ^{15 to} 5 × on the GaInAs layer surface.
10 ¹⁶ cm ^-3 , 8 × 10 ¹⁶ to 2 × 10 near the hetero interface
It is about ¹⁷ cm ^-3 . This is because by holding such a profile, high electrons can be stably obtained. The above profile can be obtained by changing the flow rate of the doping gas during the growth of the GaInAs magnetosensitive layer. As dopants, group VI element S, Se and group IV S
i. During the epitaxial growth process, the flow rate of a gas containing these dopants, for example, hydrogen sulfide (H ₂ S) or silane (SiH ₄ ) gas is changed with time. GaInA
The flow rate of the doping gas is increased at the start of the growth of the s magnetic sensing layer. The flow rate of the doping gas may be reduced toward the end of the growth of the same layer. The rate of decrease of the flow rate with respect to time may not be constant. For example, there is a method of increasing the flow rate decreasing rate at the start of the growth of the GaInAs layer, and thereafter changing the flow rate at a constant rate. The change width of the flow rate may be obtained from the change of the target carrier concentration. [0012] GaInA without intentional doping
In some cases, an s-sensitive layer is obtained. In this case, the profile of the present invention can be obtained by changing the III / V ratio. III / V
The ratio is a supply concentration ratio of the raw materials of the group III and group V elements.
To grow GaInAs, an organic material such as trimethyl In is used.
Use Group III compounds. For example, trimethyl In and PH ₃
If the supply ratio to the growth system is changed, it means that the III / V ratio has been changed. Generally, the higher the III / V ratio, the higher the carrier concentration. Therefore, the III / V ratio should be high in the initial stage of the growth of the undoped GaInAs magnetosensitive layer, and the ratio should be reduced as the growth proceeds. The rate of decrease in the ratio need not be constant. When the carrier concentration is increased in the depth direction of the magneto-sensitive layer, the occurrence of a concave portion on a conventional profile, that is, a high resistance region can be prevented. This is because the dopant acts as a donor and increases the carrier concentration in the region. Ga _0.47 I
An example of a preferable carrier concentration profile in the n _0.53 As / InP bonding material is shown by a solid line in FIG. Although the carrier concentration in the vicinity of the hetero interface (107) is increased, it is not preferable to increase the carrier concentration in the same region as it exceeds 10 ¹⁸ cm ^-3 . This is because the electron mobility is reduced.
Even without such a high carrier concentration, generation of the conventional high resistance region (108) can be prevented. The Ga _0.47 In _0.53 A produced according to the present invention
The electrical characteristics of the s / InP heterojunction Hall element were evaluated. Electron mobility at room temperature is about 12,000 cm ² / V
· S and the conventional 6,000 to 7,000 cm ² / V · s
A high electron mobility was obtained stably as compared with the room temperature mobility value of By optimally designing the carrier concentration profile in the vicinity of the heterojunction, the GaInAs / InP heterojunction material has a function of imparting high electron mobility. Hereinafter, the present invention will be specifically described based on examples. FIG. 1 is a schematic plan view of a GaInAs / InP heterostructure Hall element according to the present invention. FIG. 2 is a schematic sectional view taken along a broken line AA ′ in FIG. (101) is an Fe-doped semi-insulating InP single crystal used as a substrate. The thickness of the substrate crystal was about 350 μm. The specific resistance was 10 ⁷ Ω · cm. (102) C ₅ H ₅ on the substrate (101)
An undoped InP buffer layer grown by a normal pressure MOCVD method using In as an In source. The thickness was about 100 nm. The carrier concentration was about 2 × 10 ¹⁵ cm ⁻³ . S-doped Ga is formed on the InP layer (102).
_{A 0.47} In _0.53 As magnetosensitive layer (103) was provided. The thickness was about 10 nm. S was doped using H ₂ S (at a concentration of 10 ppm). The carrier concentration at the hetero interface was 8.0 × 10 ¹⁶ cm ⁻³ . The carrier concentration on the surface was 2.0 × 10 ¹⁶ cm ⁻³ . The carrier concentration was obtained by changing the doping flow rate. No conventional recess corresponding to the high-resistance region was found on the profile. Further, the carrier concentration on the InP buffer layer side also decreased monotonously. Ohmic input and output electrodes (104) were formed on the magneto-sensitive layer (103) by using known techniques such as photolithography and vacuum deposition. In addition, the electrode (1
The surface other than 04) was covered with a SiO ₂ insulating film (105). A part of the insulating film (105) was processed to form a dicing line (106). Table 1 shows the evaluation results of the electrical characteristics. A remarkable difference was generated between the present invention and the conventional example in the room-temperature electron mobility and therefore the product sensitivity, indicating the superiority of the present invention. [Table 1] The sensitivity of the GaInAs / InP heterojunction Hall element is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a GaInAs / InP heterojunction Hall element according to the present invention. FIG. 2 is a schematic cross-sectional view of the Hall element shown in FIG. 1 along the broken line AA ′. FIG. 3 is a diagram showing a carrier concentration profile. [REFERENCE NUMERALS] (101) InP single crystal substrate (102) InP buffer layer (103) Ga _0.47 In _0.53 As feeling free layer (104) ohmic input and output electrode (105) SiO ₂ insulating film (106) dicing lines (107) Hetero interface (108) High resistance region

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-98983 (JP, A) JP-A-5-74705 (JP, A) JP-A-6-268279 (JP, A) JP-A-60-1985 198877 (JP, A) JP-A-5-275767 (JP, A) The 53rd Autumn Meeting of the Japan Society of Applied Physics, 1992 Autumn Meeting 3, p. 1078 (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 43/06 G01R 33/07

Claims (1)

(57) Claims 1. An InP buffer layer deposited on an InP substrate
And a GaInA provided heterojunction with the buffer layer.
s free layer and ohmic electrode provided on the free layer
In a heterojunction Hall element having
From the surface on the side where the conductive electrode is provided to the InP buffer layer.
Carrier of GaInAs magneto-sensitive layer toward terror junction interface
Heterojunction characterized by a monotonically increasing concentration
Hall element.